I followed the rules and put the files on the SD card. I locked the card - however the card MUST REMAIN UNLOCKED for the load to succeed.
Good to know. So how many times did you try it first . Hahaha
Do you mean you unlocked the card, put the new files on the card, locked the card and then the PowerPlant would not accept the new firmware?
Yes, I locked the card before trying to load it. It failed to work. I then got a card from my distributor - I noticed it was unlocked but the files were identical to my card. I then unlocked both cards and because I have two P10s I left one card in each. I powered up the two P10s and both loaded the new firmware. The instructions obviously tell you to unlock the card to format it or to load the files on it - the instructions don’t tell you to keep the card unlocked!.
I expect to unlock the card to copy files on to it. But I would not think if would matter if it were locked or unlocked to perform the upgrade.