Microwave Oven EM-804T

Please advise how to fix my microwave oven.

I unplugged the microwave, unscrewed the back and took off the cover. I don't know what a voltage transformer looks like, so i played with all the connections to make sure they were all securely connected and plugged in. I then plugged in the microwave and turned it on. It started working and after 2 seconds made a loud popping noise and there was a flash of light beside where the lightbulb is. But it continued to work and this pop and flash did not reoccur. I tried it again and it worked and inner turn table was turning. I secured the cover back on and tightened the screws. But again, it did not work. Now, as before, the light comes on and the timer works, but the turn table does not turn and it does not microwave.

I opened it up again and this time played with the door switch. I took the door switch out of where it was locked into place, made sure the little button on it was working well and then snapped it back into place. i put the metal cover back on and plugged it in. I pushed the door open button to open the door and then closed the door again. The microwave turned on and worked. But subsequent times it did not, but only works if I push the door open button in by a hair and hold it in that position until cooking is done.