I will edit this post as information is updated, thanks for any help.

1. Do Not Mount X3 on OSMO before Inspire X3 Update - Upgrade the original X3 camera ON the Inspire 1 to FW_V01.06.00.40 or latest firmware.

2. OSMO Update - Upgrade the OSMO handle to OSMO_FW_BUGFIX_V01.04.01.80.bin or latest firmware.
Caution: Note the word BUGFIX in the firmware file name. Until DJI provides an update of the new firmware with a new name (e.g. .81) you need to beware of using the wrong version 01..04.01.80 as it may diable your OSMO and require it to be sent back to the factory for repair.**

Update: From DJI-Amy (see thread) delete Inspire Firmware from SD card on the X3 (or use a separate SD card without it) before the OSMO firmware upgrade. For some reason she also indicated that the firmware upgrade for OSMO after the Inspire based upgrade to X3 was optional (up to me) which seems weird.

** Apparently the same "product naming guru's" at DJI who chose to confuse their customers mercilessly by assigning two very different gimbal/camera setups with the same name (instead of, for example, calling the OSMO version X3-O) also have great influence in the Software Engineering Department. How else can you explain using the same Version Number for two firmware updates (one good,  one that can disable your OSMO)? Heads should roll.

Hi, the current firmware of Osmo is the fixed version, you can upgrade it by SD card with no problem. It's v1.4.1.80. If you've succeed to upgrade to the 25th version, there is no need to upgrade again.
About the X3 camera, please try to upgrade it on Inspire 1 to the latest version first, then delete the inspire 1 firmware and mount it on Osmo, you can choose to upgrade it by the latest Osmo firmware or not.