Solenoid?

[turbodiesel]

Went out to start the 300SDL today after sitting for around a month.. starter just spins freely but does not engauge and turn the engine.

Tried jumping it, thought maybe the battery was weak.. no good. Tried tapping on the starter with a hammer, no good. Tried spinning the starter for a long time thinking the heat generated from that will free the solenoid.. no good.

After the extended starter spinning session, the terminals on the solenoid were red hot and I saw smoke coming from them.. any ideas? The starter is a remanufactered Bosch unit which is new.. This is obviously a complication from sitting an extended period of time as I had no problems with the starter prior to this.. any ideas?