Question HELP! Dead Intel Motherboard 0KV3RP - Right before Christmas!

[Nyphrodel]

I purchased my daughter a DELL XPS 8940 in 2021. It's an i7 10700 and the other day, it just went dark. This, of course, would have to happen just before Christmas. She's driving me crazy because she feels totally unconnected to the world without it. After looking it over, I'm about 99% sure the system board is dead. I just purchased a new psu because she wasn't get enough juice. So, I went a little over what she needed and purchased a Corsair 850w because we were thinking of future upgrades. I haven't installed it because it won't fit in the case because DELL uses as much proprietary equipment as possible. Our original plan was to get rid of that proprietary psu (it looks like a shoebox, for God's sake!), get a new case, upgrade the system board, and processor. She loves her Nvidia 2070 super, so I don't need a new gpu. I refuse to buy a prebuilt system again unless I can find a spankin good deal for Cyber Monday and just swap out some of the parts. That aside, does anyone have any suggestions of where I should start? I'm loathe to spend the money that I've been saving for Christmas, so I want to go cheap, if possible. Maybe just replace the motherboard, for now...? I'd love some input because I'm super busy right now, and I can't think straight because she's driving me crazy! This is important! She just went to her room and slammed the door...AGAIN!

Best advice, please?

She uses her system for watching streamers, playing video games, and she plans on being a streamer herself in the near future.