LJ 6L All lights on after turn-on 1

[rogerfixit]

Lights indicate error condition. Goes thru start-up and 'Ready' light comes on. If I try self test, goes into error condition.
Replaced toner to eliminate that. Suspected fuser- swapped out with good one. No better.
What else can I check
Thanx

 

[hpwizzard]

When all the lights are on, there is a service error. Press and hold the front panel button to display the LED error code pattern. The code will be shown only while the button is pressed. Check this link for an explanation

http://www.hp.com/cposupport/printers/support_doc/bpl03383.html