i started having issues at about the 10month of usage

LiPo batteries should not be drained to zero and should be allowed to go to about 50% before recharging

my thought process in analyzing your problem is:

1) first fully charge battery
2) then reflash to the current OS using a fresh image
3) do not restore from a backup
this will help determine if it is hardware or software related if problem persists it is either the n810 or a battery issue- it is faster to buy a battery than to send in the n810 for repair . if it is the battery- all will be fixed if it isn't then send to nokia for warranty repair and you have a spare battery

4) if after reflashing it works aok then it is software related... add program after program individually until problem reappears.....