I have tried updating the H710 mini via iDrac7 Enterprise(both Local, HTTP, HTTPS, and maybe FTP), and through the ISO (PER620_BOOTABLE_20.04.00.126.iso). I tried (newest) SAS-RAID_Firmware_KKR9J_WN64_21.3.5-0002_A09.EXE, (update right after current ver.) SAS-RAID_Firmware_X7R5G_WN64_21.3.1-0004_A06.EXE for a local install through iDrac. I tried reseating the raid + pci devices except the network daugher card which requires special tools. No luck. Have not tried directly through the LCC though because it would required other network changes. What is also odd is the rest (4-5 packages/firmware) of the hardware updated with little to no issue?
have you checked, if there are any running background tasks at the moment when you do the update?
The firmware upgrade may fail if any of the RAID controllers in the system are performing an I/O background task (that is, consistency check, background initialization, rebuild, or reconstruction). Allow the background task to complete before attempting to upgrade the firmware. Patrol Read tasks will not affect a firmware upgrade.
In order to remove the NDC, please follow these steps (no special tools needed).
Using a #2 Phillips screwdriver, loosen the two captive screws that secure the NDC to the system board.
Hold the NDC by the edges on either side of the touchpoint and lift to remove it from the connector on the system board.
Slide the NDC away from the back of the system until the connectors are clear of the slot in the back panel and lift the NDC out of the chassis.