MKS Gen L problems. (3 replies)

I have a FLSUN i3 printer with an MKS Gen L v1 mainboard. I am at the end of my rope as I have been trying to get this printer running for over 2 months with no success. it had been running for 5 years without any issues, but I flashed it thinking it would work better.
I have tried Marlin 1.0.x 1.1.x and 2.0.x. I have had board in the config.h file listed as both BOARD_MKS_GEN_L and BOARD_RAMPS_14_EFB. Marlin 2.0 uses the Ramps board in the config. Can I change it in 2.0? If so, How?
With 1.0 and 1.1, the dual Z steppers (Driven off 1 driver) do not move in unison, or there isn't any movement from the printer when I give it a command or the heaters will not work. The issues differ from one flash to the next.
With 2.0, the printer moves fine, but takes takes forever get up to temp. The printer has been running for 18 minutes and the bed is still only at 52 out of 60 degrees. It will not go higher.

I do not have any auto levelling installed and the printer is basically stock.

I tried to read about possible fixes, but I have ADD and I have a difficult time concentrating on what I am reading, so I skim over it.

If I could get the original firmware for this printer, I'd love that, but I can't find it anywhere. FLSUN doesn't support the printer anymore and all the config.h files I find have been modified by someone.

Any help would be great.
Ian