Was sold a faulty Christmas gift

On my 2nd round of unemployment due to covid again and struggling enough because I recently found out my injury I’ve had since August is 3 herniated disk in my neck and will need surgery so I’m definitely out of work. I went to a local pawn shop to see what kind of gadgets they might have (looking for a cool VR system) and came across a custom gaming PC I checked it out and put it on layaway with 70 dollars down and the whole thing being 550 out the door. Paid it off at the end of November, immediately wrapped it and put it under the tree. Christmas morning comes and he is so excited I’ll try to upload the video he starts downloading fortnite and planet coaster he starts to play fortnite and it keeps shutting off on him with some messages of “motherboard” followed by a cmos failure screen next. I replaced the cmos battery and checked temps and put the motherboard disk in to do a update nothing is working. I feel like a failure because this is all that he wanted and this is all he got for Christmas. He’s a good kid especially for being 14 years old. Covid really screwed with out very active fun lifestyle and if anyone on here wants to donate it will definitely go to a good cause and make this 14 year olds year! Depending on how much this can do I will do 1 of 2 things either “fix” this very old out of date failing computer or buy a new one and will show receipt!