Diagnosis
Total power loss usually points to a blown thermal fuse (a safety device on the motor), a failed main control board, or a loose internal connection. On these Bosch models, a power surge can take out the board.
How to Fix It
Do a hard reset first. Unplug the machine from the wall for a full 5 minutes. While it's unplugged, press and hold the Start/Pause button for about 10 seconds to discharge any residual power. Then plug it directly back into the wall outlet (not a power strip). Listen for a faint hum or click and check for any display illumination.
If That Didn't Work
If there's still absolutely no sign of life, the next common culprit is the door lock switch. If it fails, it can prevent the machine from powering up as a safety measure. You can sometimes hear a faint click from the door lock area when you close the door if it's working. Testing or bypassing this requires opening the machine and is a bit more involved.
Heads Up
Before you call a tech, double-check that a household GFCI outlet hasn't tripped. Also, Bosch washers are known to be sensitive to being plugged into outlets with other high-draw appliances—try a different, dedicated outlet if possible to rule that out.