It could be a corroded or broken wire perhaps even lose wire Make sure bulb is all the way in and turned and inside connections or contacts are not corroded
4000 RPM'S is not good on your engine if it was an automatic I would be concerned about it not shifting gears as a manual I wonder if your transmission is actually shifting as it should
Try not using the popcorn button Set it for 3minutes watch over it and when popcorn stops for 2seconds between pops it is done This may be due to wrong settings for the button or wrong time setting for it making it either too hot or making it go for too long
Also be sure to check for a foil covering inside of wire this is a ground connection if there I believe the wires are as follows but you may have to experiment a bit Blue is Left Green Right Red is mic Any other wire/foil would be the ground wire
Try taking out the battery for 10 minutes Charge until 100% Pull it again 10 min. Put into phone- turn on phone - reset phone I hope this helps it works on mine sometimes Make sure cords have a nice snug fit