To quote Sony PlayStation on the PS Vita System Software 3.12 Update via Twitter:
Heads-up - PS Vita 3.12 system update launching soon, improves system stability during use of some features
To recap from the previous article, what the PS Vita 3.12 Firmware Update fixes: Some PlayStation Vita consoles with 32 GB Memory card either shut themself down or go into a constant reboot after installation of PS Vita Firmware 3.10 Update.
From Infamous_Hero via Reddit: "I updated my Vita after fully charging it, now it won't turn on. The PS logo appears on the screen and the home button turns blue but then turns off seconds later."
Also from Oguri_Kureno: I have spoken to Sony Technical Support this morning after my Vita crashed during the 3.10 update.
I have two Vita's neither will boot with the card in, and neither will enter Safe mode with the card in.
The rep confirmed it's an issue with "some memory cards", they wouldn't confim which ones.
There is a patch dropping tomorrow to fix this issue apparently. The advice was:
Remove the memory card
Update the with the new patch
Re-insert the card to see if the data is available.
I would personally then (if you have access) back up the save game data and format the card but that's personal opinion.
I thought I would create this thread for other having the same issue.