We have an Optoma HD200x projector which is switching itself off after 30 seconds. The LED indicators show "error lamp fail" although the lamp lights each time. You can hear the fan working.
The projector seemed to be working when we first got it (we inherited it with the house we bought but after 2 films it stopped working)
It has been in a dusty environment and never cleaned by the look of it. I took it apart and cleaned it but with no change in how it works.
Both fans inside it work fine when connected to a 9V battery.
None of the capacitors on the logic board appear to be blown. There is no obvious heat damage and no smell from it...
Any advice or ideas gratefully received.

Many thanks