The best I found if u want to repair it estimate:
Replace batteries (it is a dual plastic bag set) w same 8hrs (note: new surfaces claim 12 hours)
clean motherboard bc corrosion underneath due to leaky battery (swelling will do this)
replace screen bc after budge it cant be reattached wo breakage. (surface 4 has an unusually thin screen with Gorilla Glass 4)
$180 w 1 year warranty, 2 b-day turnaround if no corrosion, 3-4 if there is.
This is from a 1 man cell and tablet repair shop in Manhattan, NYC. I suspect others can do it too. The chain repair shops are much more expensive than this. I suppose you can then try to send the bill to MS or arbitration or small claims court. Since a lawyers time is in the hundreds per hour, MS might just want to pay it. It likely that your own time, pain and suffering, inconvenience, etc wont be compensated.
But why continue with this POS - switch to any other brand.