No display on control panel, e7-90 & u2-05 error on mx4101n

[r4roty]

Please help offer solution(s)
No display problem was solved by replacing blown out fuses 2nos on 24v2dc and 24v3 dc on the DC power supply unit .
When the power was cycled , the machine failed to boot -up instead it threw up a U2-05 first and then an E7-90 all within 10secs.All output dc voltages on the PSU are correct viz 3.3v,5.0v,12.0v,24vdc respectively.
All harnesses between the PCU & the Mother board as well as between the mother board & the MFPC boards were checked OK. Moreover the machine cannot enter simulation.The only fan running is the fan on the MFPC
Where could the fault lie, the PCU or the MFPC or both?

[1090tech]

Does the touch screen respond at all when touched?