Dell xps 15 L502X, Facing so many problems after BIOS upgrade..

Hello tech's, i am using Dell xps 15 l502x for the past couple of years

the laptop was running really good, Few months before i upgraded my BIOS from factory
version to the current version A12. After upgrading the BIOS i am facing several kind
of problems. Like, The system won't startup on first attempt, The battery has to be
removed and put pack again for more than 3 or 4 times for the system to startup, After the
System starts up everything will work fine just for 5 or 10 mins and after that Touchpad and
keyboard will become inactive, But the Keyboards back-lit LED will be working and
lighting up, I have to restart my system again to make it work, Sometimes it will work fine
Sometimes it will not, The system will suddenly crash and end up in a bluescreen error, So
Then i have to remove the battery and put it back to get it work. Sometimes when i shut down
the system, It will not, The system will stay at shutting down... Window for prolonged hours
so again i have to remove my battery to shut it down..

The biggest problem is the BIOS, it is not showing my service tag and asset tag there, Instead i
see a symbol like Y and two dots on top of that. Due to this i cannot run dell's online
diagnostics tool through dell setup, Dell is not recognizing my service tag automatically. I upgraded my BIOS just because dell recommended me, And i am facing so many issues now. What should l do now to make my laptop work fine?