Please keep in mind this is a crashed drone, I replaced shell & motors and landing gear.  I do not have bottom shell installed.  I get good tones but then get 4 solid red lights - critical  I hooked up app and try to do calibration.  I get to 8% and fails due to temperature out of range.  Drone is supported and sitting vertically, I rigged a gig to use a muffin fan to blow on heatsink without touching it.  It gets to about 18% sometimes then fails, my record is 36%.  Is this IMU board damaged?  Do I need to replace it?  Where can I get one and how much is it if I need to get one.  Thank you!

Hi there, did you get any error codes when IMU calibration failed? Or had you checked the firmware of your drone, upgrade it if it's needed.
Since the drone had crashed, I would recommend sending the drone back for repair.
Here's the online repair link: https://repair.dji.com/en/SelfRepair/Area …
Send it in if you need and we will do our best to help this out. Thank you.

send it back to dji - something is 100% wrong, i doubt this is something you can get past.