Diagnosis
This indicates a partial power failure. The control board is not initializing. The most likely cause is a blown internal fuse on the main control board or a failed low-voltage power supply section on that board.
How to Fix It
Unplug the oven for 5 minutes. Plug it back in directly to a wall outlet, not a power strip. Listen for a single beep and watch for a display flash. If nothing, the internal fuse needs checking. This requires disassembly to access the main control board, typically behind the front control panel. Locate and test the 5x20mm glass fuse on the board.
If That Didn't Work
If the fuse is intact, the main control board has failed. The faint hum is the high-voltage transformer under standby power, but the logic circuit on the control board is dead. The entire main control assembly must be replaced.
Heads Up
Do not attempt to jump or replace the fuse with a higher-amperage rating. The fuse is a safety device. If it blows again immediately, there is a short circuit elsewhere that must be found first.