W reg Renault Scenic. I recently needed to extract my radio to get the serial number (needed the code).
The thing was quite badly jammed, and in the process of removing it, the front panel came loose.
Now the radio is completely dead - even the clock display on the dashboard has gone. I've pushed the front panel back on & it seems quite secure, and all the wires at the back look okay. I can borrow a multimeter, but I don't have much of an idea what I can check.
Well something might have came loose or broken inside, probably something connected to the front panel itself (like the display connector), if you are not familiar with electronics I would have it looked at since probably you will further damage it, there is a tool to remove those safely so you missed your chance to stay out of trouble.
There could be a variety of issues that could cause an issue like this. Checking the fuses is a good idea, but make sure to check ALL the fuses in the vehicle first since it would be the easiest resolution.
Also, before pulling any electronics from any vehicle, it would be recommended to disconnect the Battery to prevent any electrical damage. If you did not do this, there is a possibility that it could be fried.
Furthermore, if it truely isn't fried, sometimes Factory Radios will lock themselves as an Anti-Theft feature. I would suggest contacting your Local Dealer and check to see what steps you will need to unlock it.
Im not sure exactly how "loose" the front panel became, but it is very possible that a wire or some cable may have come undone internally. If you are good with taking apart electronics, try slowly taking it apart and see if you can find any internal damage or loose/disconnected parts.
If all else fails, looks like you'll need to get it refurbrished or purchase an Aftermarket Deck.