As Mika said first step is to measure the PSU output to make sure it is supplying voltage… If there is no load this could be a fake reading… I.e the PSU will be fine with no load… but it is possible for the PSU to shut down as soon as a load is supplied so it might be best to measure with the SimuCUBE board attached to make sure it is working… If it is not supplying voltage, you will most likely just need to change the PSU.