Why does nobody warn you about BIOS updates on old shop machines?

Last Tuesday I ran a routine BIOS update on a client's 2016 Dell OptiPlex at the shop and it bricked the board halfway through, no post, just a blank screen and a fan spinning. I had the machine on a tired UPS I should have swapped out months ago, and sure enough the power dipped right in the middle of the flash. I pulled the CMOS battery, tried a recovery USB, and nothing worked, so I ended up swapping in a spare board I had in the back. Now I check the UPS load and battery health before any flash, and I keep the recovery file on a stick taped inside the bench drawer. Has anyone found a recovery trick that actually works on these older Dells, or is a spare board the only real backup?