New laptop crashes

[gebbeth]

I just bought an ASUS G751JL with 16 GB ram (upgraded from store - 12 GB originally), i7 4720, 128ssd, 1tb hdd, gtx 965M 2gb.. It came with Win 8.1. Every time I try to update it, it crashes (BSOD). Asus Tech Support told me that it might be the upgraded memory and I should return it. The seller told me that it's a software issue and the way they sold it, it is working fine. If I try to update it, it is my problem. What is happening here? Who should I listen to? Please help

 

[TechyInAZ]

Try updating the BIOS.

 

[gebbeth]

Try updating the BIOS.

I see. It also shuts down randomly and doesn't turn on unless I hold the power button for 20 sec. I don't know if that is BIOS related, too. The most important: how do I update the BIOS?