Estima 2003 Dead Speedo Cluster = wont start???

[Master of disaster]

Hello folks. I have had this bus for four years, previously sons for two years.Only problem it's ever had was Engine M light on for those years.MOT 2018, it  failed emissions. New Cat and two new Lambda sensors fitted by garage (because I was working) that did MOT, cost £700. Passed MOT despite EML still being on.

This year as usual I checked all bulbs by turning on all lights (block of wood brake pedal to seat) to check for any earth problems, with engine running and off, everything OK. Then someone turned up, and I had to go out.The next day, I realised the ignition and lights had been on until the Battery went flat.

So after charging the Battery, I turned the key, the only lights that came on were on the column ABS EML and Handbreak. Speedo Cluster was dead Inc fuel and temp.Indicators and Main Beam work.Turn the Key and nothing, not even a click.Battery showing 12.9 Volts.

I have checked all fuses (replaced 7.5 under left dash), left dash right dash and under bonnet and big ones with windows, borrowed a Relay tester checked under left dash board and under bonnet all OK.Does anyone know if there is a Voltage Regulator on the Speedo board that might make a difference.I haven't got a wiring diagram either which doesn't help, and all exterior lights are still working.

So before I call in a vehicle electrician, I would appreciate any suggestions from the forum.