Question:
We have an HP Laserjet 4345MFP  that was printing fine the other day. Today, when we turned on the printer a 55.00.00 DC Controller Error displays on the printer.  I have shut the printer down several times and the printer keeps displaying an error.  Does anyone have a direction to take with this.

Solution: 
The next step is to replace the DC Controller.  

Note:  There are two different models.  HP Laserjet 4345MFP and M4345MFP.  The Controller may be different .   Check Partsufer in order to verify the correct part number.

Update:  Below part number covers both models.
RM1-1354-000 – DC Controller HP Laserjet 4345MFP  / HP Laserjet M4345MFP.