I have tried to update the firmware for my mavic air from v1.00.0400 to v1.00.0500 via dji assistant 2 latest version.  The update kept getting to 91% installed, the mavic air would restart and then the upgrade failed.  I turned off all anti-virus.  I tried on a different PC, I tried via the RC controller and all had the same effect. Now when I connect the mavic air to the PC the USB device tries to install but cannot.  When I connect via the controller the Mavic Air is not recognised.  If I try to connect via WiFI there is no wifi signal recognised.  
I have tried clean installs of software, removing all drivers, different PC's but no luck and rapidly running out of patience.  Firmware updates have always worked OK until now.

Any advice on what to do next would be greatly appreciated.
  

Sounds like the FW has corrupted the drone. After troubleshooting everything that you appear to have done I hate to say it but you may need to ship it back under warranty.

Oh yes, I am running windows 10

Hi there, sorry for the inconvenience. Please download and reinstal DJI Assistant 2 using this link: (https://www.dji.com/mavic-air/info#downloads) and then install this driver to your PC: (https://drive.google.com/file/d/0B4jKLmmRYhQaX3pYOXJRWkpzSFE/view). You can also try a different cable so that we can isolate the issue. Just download the driver - Open it - Choose "run"- Select your language - Power on device and connect it to pc via usb - Click Next- Click Next again- Install. Please let me know if your RC still can't connect to your PC. You can also follow the video tutorial below on how to properl update the firmware using DJI Assistant 2. Thanks for your support.

DJI Paladin Posted at 2018-10-29 04:46
Hi there, sorry for the inconvenience. Please download and reinstal DJI Assistant 2 using this link: (https://www.dji.com/mavic-air/info#downloads) and then install this driver to your PC: (https://drive.google.com/file/d/0B4jKLmmRYhQaX3pYOXJRWkpzSFE/view). You can also try a different cable so that we can isolate the issue. Just download the driver - Open it - Choose "run"- Select your language - Power on device and connect it to pc via usb - Click Next- Click Next again- Install. Please let me know if your RC still can't connect to your PC. You can also follow the video tutorial below on how to properl update the firmware using DJI Assistant 2. Thanks for your support.

Thanks I did exactly this.  Problem remains that the PC cannot set the driver up properly for the Mavic Air and seems to get stuck in a loop of trying to install device drivers over and over again.  I noticed that when I installed the software there were some lines of code in the command window showing that some files had not been installed due to hash errors - the problem was the exe ran so quickly I could not get the exact details.

A CW Posted at 2018-10-29 03:36
Sounds like the FW has corrupted the drone. After troubleshooting everything that you appear to have done I hate to say it but you may need to ship it back under warranty.

It does seem that way - beautiful weather here today and had been hoping to get some of that Autumn colour in our local woods.  DoH!

freexspear Posted at 2018-10-29 05:03
It does seem that way - beautiful weather here today and had been hoping to get some of that Autumn colour in our local woods.  DoH!

It is very frustrating at times - fingers crossed for you mate

freexspear Posted at 2018-10-29 05:01
Thanks I did exactly this.  Problem remains that the PC cannot set the driver up properly for the Mavic Air and seems to get stuck in a loop of trying to install device drivers over and over again.  I noticed that when I installed the software there were some lines of code in the command window showing that some files had not been installed due to hash errors - the problem was the exe ran so quickly I could not get the exact details.

I found this in the windows error logs.....

Log Name:      Application
Source:        Windows Error Reporting
Date:          29/10/2018 12:58:11
Event ID:      1001
Task Category: None
Level:         Information
Keywords:      Classic
User:          N/A
Computer:      Dining-Room-Len
Description:
Fault bucket , type 0
Event Name: PnPDriverImportError
Response: Not available
Cab Id: 0

Problem signature:
P1: x64
P2: E000024B
P3: dji_vcom_driver11.inf
P4: af374644b56e73c8d38118255ac632894b89ea57
P5:
P6:
P7:
P8:
P9:
P10:

Attached files:
\\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER13D2.tmp.WERInternalMetadata.xml

These files may be available here:
C:\ProgramData\Microsoft\Windows\WER\ReportArchive\NonCritical_x64_64c3a85dd2a9d2a95cfd8a60fc3932a23fb46c8c_00000000_4220171e

Analysis symbol:
Rechecking for solution: 0
Report Id: 13e8a80c-a2d5-4ec1-9762-997f0f13112d
Report Status: 2147491840
Hashed bucket:
Cab Guid: 0
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
  <System>
    <Provider Name="Windows Error Reporting" />
    <EventID Qualifiers="0">1001</EventID>
    <Level>4</Level>
    <Task>0</Task>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2018-10-29T12:58:11.436153900Z" />
    <EventRecordID>10113</EventRecordID>
    <Channel>Application</Channel>
    <Computer>Dining-Room-Len</Computer>
    <Security />
  </System>
  <EventData>
    <Data>
    </Data>
    <Data>0</Data>
    <Data>PnPDriverImportError</Data>
    <Data>Not available</Data>
    <Data>0</Data>
    <Data>x64</Data>
    <Data>E000024B</Data>
    <Data>dji_vcom_driver11.inf</Data>
    <Data>af374644b56e73c8d38118255ac632894b89ea57</Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
    </Data>
    <Data>
\\?\C:\ProgramData\Microsoft\Windows\WER\Temp\WER13D2.tmp.WERInternalMetadata.xml</Data>
    <Data>C:\ProgramData\Microsoft\Windows\WER\ReportArchive\NonCritical_x64_64c3a85dd2a9d2a95cfd8a60fc3932a23fb46c8c_00000000_4220171e</Data>
    <Data>
    </Data>
    <Data>0</Data>
    <Data>13e8a80c-a2d5-4ec1-9762-997f0f13112d</Data>
    <Data>2147491840</Data>
    <Data>
    </Data>
    <Data>0</Data>
  </EventData>
</Event>

freexspear Posted at 2018-10-29 05:01
Thanks I did exactly this.  Problem remains that the PC cannot set the driver up properly for the Mavic Air and seems to get stuck in a loop of trying to install device drivers over and over again.  I noticed that when I installed the software there were some lines of code in the command window showing that some files had not been installed due to hash errors - the problem was the exe ran so quickly I could not get the exact details.

Here will show you how to reinstall the drivers using Device Manager on PC:
1. Power on the aircraft and connect it to PC via USB cable;
2. Select the Start button on PC , type Device Manager, and select it from the list of results;
3. Expand one of the categories to find the name of Unknown device, then right-click it, and select Update Driver;
4. Select Browse my computer for driver software and click Browse and go to where the drivers located (Sample: C:\Program Files\DJI Product\DJI Assistant 2\Drivers);
5. Click Next and then the drivers will be installed.
After installing the drivers, re-plug the USB cable and launch DJI Assistant 2, then the Unknown Device should be gone from the Device Manager and DJI Assistant 2 should recognize the aircraft.

If the issue still persists, please disable the digital driver signature on PC.Kindly use this link: (https://in.c.mi.com/thread-28161-1-0.html). Please let us know if the issue persists. Thanks for your support.

freexspear Posted at 2018-10-29 05:08
I found this in the windows error logs.....

Log Name:      Application

Thanks I tried all of the above.  The drivers were properly installed after I disabled windows validation and I got messages to say that the drivers were installed anyway.  After trying with and without restarts the problem remains the same.  Device manager reports unknown device, I tried updating the driver but still the device is not recognised.  It seems that the computer just cannot recognise the device even with the correct drivers installed.  As this now happens on any PC and the Remote control can no longer link and the wifi connection does not work anymore the Mavic seems to be incomminicado.  It is still in warranty and a have DJi refresh as well.  What should I do next?

DJI Paladin Posted at 2018-10-29 08:00
Here will show you how to reinstall the drivers using Device Manager on PC:
1. Power on the aircraft and connect it to PC via USB cable;
2. Select the Start button on PC , type Device Manager, and select it from the list of results;

No luck problem remains the same the mavic air cannot be seen by any PC, the remote or turn on its own wifi.

freexspear Posted at 2018-10-30 06:37
No luck problem remains the same the mavic air cannot be seen by any PC, the remote or turn on its own wifi.

I'm really sorry to hear that. I would recommend you to contact our support team to start up a case: (https://www.dji.com/support?site=brandsite&from=nav). We have the professional data analysis team who would do their best to find out the reason of the issue and then the corresponding resolution would be provided, thanks for your support.

DJI Paladin Posted at 2018-10-30 07:00
I'm really sorry to hear that. I would recommend you to contact our support team to start up a case: (https://www.dji.com/support?site=brandsite&from=nav). We have the professional data analysis team who would do their best to find out the reason of the issue and then the corresponding resolution would be provided, thanks for your support.

OK thanks - will do.

freexspear Posted at 2018-10-30 07:01
OK thanks - will do.

You're welcome. I hope everything goes smoothly.

Another thing you can try, is run DJI Assistant under compatibility mode, maybe Windows 7. However, if Windows is not detecting the drone, then DJI Assistant will be useless anyhow.