Salvaging a failed gen one Tricolour Mendel build

So have bought a Tricolour Mendel back when they were pretty new, I've hit the same bump in the road every time I've tried to wire it up. basically, half the multi-meter readings come out wrong if I wire it according to the instructions, and if I bridge the two positive pins on the XLR socket in the printer, the readings come out correctly, but the two melzi boards will not talk to any computer, which has been the case even when I've tried updating the firmware according to the instructions. Each time I've failed, I've asked a few questions on the rep-rap forums and gotten no solutions to the issues. I'm writing this after my third attempt at re-wiring the entire thing from scratch, this last time with fresh wire and cable bought solely for this purpose and according to the original specifications.

I'm basically ready to give up on ever getting this thing to work as is, and would like to know if there are any single boards out there that would support the following as a minimum:
1 X X stop
1 X Y stop
1 X Z stop
1 X X stepper motor
1 X Y stepper motor
2 X Z stepper motor wired together in parallel
3 X extruder steppers
3 X 40mm fan
3 X 100k thermistors
1 X 10k thermistor
3 X heater cartridges

Steppers are Nema 17's

I suspect I may also need a power supply for it, but the existing one offers outputs as follows
3 X +12V 20A
3 X -12V 20A

I really don't want to use the melzi boards anymore, as I've found having to clamp multiple loose wires in a singe terminal clamp to be extremely frustrating

TLDR: I need a controller board for X Y Z Bed and three hot ends and extruders

Look at the RepRap Duet 0.85 with expansion board. Pricy but up to 6 extruders. Pancutt Devices also makes an Azteeg board with 5 extruders