Will admit that this is a new one on me - a power supply that can run the system but is not enough to power the display. Probably the only way to discover is a physical examination of the power supply.
Also is the same in English "Stupid Question" is one that is so basic that it could be considered insulting must be asked (e.g. "are you sure the power supply is plugged into a live socket.) as part of proper troubleshooting.
Just repaired a ceiling fan for a friend. Said had failed after a bad rainstorm. Power checked out everywhere but when I pulled the wall switch, it just fell out, no connection to the wires. Unit was a battery operated RF system and the battery was dead. Never say never.
Even so it is unlikely that an online forum would consider that the power supply might be the wrong one.