The P2015 series is known to have widespread formatter board issues. In most cases where the printer does not respond, it's usually related to the formatter board. This problem is very common and becomes worse as the printer ages. The P2015 series is a lemon, and is not reliable.
The USB fix is worth a shot at this point, but be aware that the odds of the fix working are not in your favor. If you continue having problems with the printer, it's going to be caused by a bad formatter board.
The good news is the issue is repairable, but the bad news is the repair is temporary and always seems to come back. I have made a suggestion on what I feel will help the repair last a little longer, but it may not work. If you are thinking of buying a new board do not waste your time or money; even the refurb boards die.
Reflowing it does salvage the printer, but this is as far as I'd go if I was going to try to repair the printer. Just make sure you use a oven you never plan on using for food to repair it. It's new enough to have a RoHS compliant board, but you still do not want to get the chemicals in your food. The only difference in tearing the printer down is going to be the amount of cables, depending on if it is a base model, network, network/duplex or network/duplex/add'l tray model.
If you do opt to try reflowing the board, here's how to do it:
- Step 1: Remove the formatter board. The board is on the side where the USB and Ethernet port are. To remove this panel, push it out with a flathead screwdriver.
- Step 2: Once you have the panel off, take a picture of the wiring and keep it for reference. It shouldn't be possible to mix up, but if it's your first try you might want this image. The network/duplex and network/duplex/add'l tray is going to have more wiring then a base model.
- Step 3: Remove the formatter board screws and unplug the cables going to the board. You will see ~4-5 screws holding it in. If you are not sure you can remember where each screw went, lay them how they came out of the printer but they should be the same.
- Step 4: Find a way to lift the board in the oven. You can do this with anything, but it needs to be 100% flat for this to work correctly. PC standoffs go a good job at this, if you can get some.
- Step 5: To extend the life of the reflow and improve your odds, put liquid flux under all of the chips on the board. The idea is your reflow will be more consistent this way. Just make sure to use no-clean flux or ultrasonic the formatter board after baking it to clean it.
- Step 6: Preheat the oven at 450-500 degrees for 5 minutes. Put the board in until the solder is molten, then remove it. This takes around 5-8 minutes. DO NOT BUMP THE BOARD. Let the board cool for 8-12+ hours.
- Step 7: If you used a oven you cook food in, run a cleaning cycle and clean the oven throughly. If the oven is disposable, clean it a little and put it away.
- Step 8: After letting the board cool, put it back in the printer and try your luck.
Some advice I can give you that might extend the printer's second run is a heatsink. Get a heatsink large enough for the 2 main chips (Processor and Ethernet controller) and mount them. The glue on the back should be sufficient, but if you want to be sure they will not move use thermal Epoxy.