After driving through high water, it took a few days of drying out plus new spark plugs and coils to get my 2016 Corolla running. It is still misfiring on cylinder 1 and has low compression on that cylinder, 90 psi, versus 150 psi for the other cylinders. Could this still be an electrical problem or is the engine damaged?
No, there's nothing electrical in there. It's just a piston moving inside a cylinder. Either you have failed piston rings, or the engine ingested water and bent a rod.
If you're lucky. There's a tiny chance the piston ring just has some rust on it and is getting hung up. You could try soaking it in some lube.
Could this still be an electrical problem or is the engine damaged?
Huh? How could low compression possibly be caused by an electrical problem?
If you do a wet vs. dry compression test or a leakdown test that should tell you whether the low compression is being caused by valves or rings/cylinder.
