My 93 Mazda mx-6 won't shift past 2nd gear

My 93 mx-6 won't shift past 2nd gear, it just revs at high rpm's and will drive but only in 2nd. The OD button won't even engage 3rd doesn't work either. Now that I drove it a short distance a slight burnt smell is on the transmission fluid dip stick. I checked the fluid and it was really full, way too much it seemed. I have tried the stop slippage thinking maybe that would work, and also I have disconnected the battery for 20 minutes then reconnected still nothing. Anyone know what could cause this it has 150k miles it's a 93 mx-6 I4 automatic transmission. I'm desperate.

Thanks