dean wrote:

I didn't adjust anything, I simple tapped here and there and then it
was ok for a few months.

What happens is that it seems not to know to stop pulling or pushing,
the motor keeps on buzzing really loud. It must be the switch that gets
hit by the stop on the chain, but its really hard to tell what's
happening, it goes really fast!

Garage door openers are designed to shut off after 20-30 seconds, in
case the travel limit switches or safety mechanisms fail, and it's
possible this is what yours is doing. I would try adjusting the lower
limit, and if it's working normally you should be able to make the door
stop several inches above the bottom. Otherwise I would unplug the
power and look for obvious mechanical flaws. If none can be seen,
remove the circuit board and examine it under bright light and a
magnifying glass for cracked traces and solder. Solder cracks can be
difficult to see, and it may be best to simply resolder all the joints
for connectors, switches, and large or heavy components. Use a
conventional 25-40W iron, not a Cold Heat iron or a soldering gun. If
possible, post a picture of the opener and its circuit board.