[Samsung Galaxy S7 Edge Questions and Answers] Vyraal1:
Apologize if this is the wrong forum as most threads I've seen on here are usually software related, but wanted some technical input.

Goal Get a working phone again for the cheapest price, bonus points if I learn something along the way, am okay with accepting the risk of ruining my 'broken phone' even more.

Samsung S7 Edge DUOS broke (no response to charging, no LEDs or lights at all) while traveling in Europe. Took it to a Samsung Paris service center and they said they were pretty sure it was a motherboard problem and I would need to send it back to Asia to fix it, especially since it was DUOS.

I'm probably going to order up a new motherboard myself and attempt a DIY repair, partially to save money, but also for enthusiast purposes. No experience with my phone, but tinkered with computer hardware before (delidding Intel CPU for overclocking purposes and did minor case modding).

1) I see different motherboard models such as for Verizon, AT&T, etc. But the physical specs of all of them seem very similar (minus the DUOS), does that mean I can buy a non-DUOS board for my phone bezel/case/camera? I got it originally from my brother and have no interest in dual-sim capabilities at all. If it means I can get another similar performing board with domestic US shipping (most used DUOS boards on Ebay/AliExpress ship internationally), I would rather prefer that.

2) Anything I can do to make sure it isn't a motherboard problem? Given the backstory and only 2-3 minutes of testing in the back (not sure how long it would take a technician to hook it up to a multimeter), the service center rep said he was pretty confident it's a motherboard issue.

3) Anything I should look out for? Make sure the motherboard doesn't have a blacklisted IMEI? I'm actually a bit unfamiliar with phone hardware, are the drives, RAM, etc. all complete with the motherboard? Or are those externally hooked up elsewhere in the phone? The prices of the motherboard complete set seem to be pretty cheap to me ($60-$100 range).

Backstory

Received it from my brother who bought it in the Philippines. The most physical damage it's ever taken was slipping out of my pocket while sitting and hitting a hardwood floor, phone worked fine for months. While driving one hot day, my phone just died while using the GPS, last I checked it was about 70% battery, and then the screen turned black and got very hot. After some googling, I waited for the phone's battery to die before charging it back up, and sometimes made it to my home screen/photo gallery, and other times got stuck in a boot loop. It would still have a blue LED indicator on the front, while being hot, and could boot the phone up in recovery mode. Although it kept giving me partition not found errors.

Did a factory reset and for some reason it miraculously worked. Re-downloaded apps as I needed them and phone seemed to work just like new again. Then 2 weeks later on the plane way to Europe, was using an GBA emulator for an hour or so, before closing the phone to sleep. Woke up to the phone very hot to the touch, non-responsive, no LED's, figured I would try waiting for the battery to die down before plugging it in again - no luck.