2 things you can do.
1. Take the lamp out and then reseat it.
2. If this happens again, let it power off by itself. May take 10 minutes then turn the main power switch off on the rear.
Wait a minute and turn back on.
*These 2 items are what Epson support will recommend if you call/request support.
If that doesn't work, then request a bulb replacement if possible because that's the next step.
This issue has plauged the 50xx line since the release. I've had no issues since having the bulb replaced under warranty over a year ago.
Prior to that, this issue would happen about every 5th to 10th power up.