Another day another case of a bad capacitor.
The unit refused to power on at all.
Upon cracking open the unit it was apparent that C316 (1000uf 10v) capacitor was bulging and needed to be replaced.
Replaced the faulty capacitor with the follwing:
CAP ALUM 1000UF 20% 10V RADIAL (RUBYCON ZLJ) Digikey Part #: 1189-2174-ND
Power supply board.
Replaced C316. All working.