Acer Beamer P1385 W "Lamp" LED blinks red and beamer turns off after 20 seconds

Hi folks,

I have a problem with a beamer I just bought. The seller told me that he hadn't used the device for a longer time - and that he's only used it several times. It arrived purely cushioned, so I reckon that this might be a cause for the problem. We hat one cinema-evening where the beamer worked perfectly. But the next time (one week later), when I wanded to use it again, it didn't start any more. When you turn it on, the blue LED blinks 6 times and then stays on - I guess this is normal. But the red LED starts to blink from that moment when the blue LED stays lighted. After about 20 seconds the beamer turns off automatically. The lamp does not work all the time. I disassembled the lamp, it looked quite okay, no black sediments inside.

Do you have any idea what might be wrong? In the manual it says that if the red LED blinks the colour wheel might be defective... But can this be the case for the beamer worked properly one eventing?

Thanks in advance!
Luke