PRS-T3 Backgrade version software

Hi all, long time no visit here:)

Does anybody know if it is possible to downgrade the PRS-T3 firmware to a version before 1.1.01.17210 the Kobo upgrade.

I have been having problems with battery life, (changed the battery not that), and it seems to have started with the Kobo firmware upgrade.

I have heard of others with this problem but no solution.

Thanks,
Rog