So, I just finished building up my Losi XXX-T-CR. I decided to swap electronics from my B4 and put them in that truck. The set up is a Traxxas servo, Mamba max pro esc and Trnity Duo motor(sensored). First run was good. Motor temps did get pretty high. After about fifteen minutes later, after screwing around with different receivers, I turn on the esc and I smell this horrible smell. Like really discussing. I thaught it was my cheap RX. I sniff around. Bam, I sniff the motor and I am buzzzed. So, I realised that the motor is getting reeeeeeaaaaaaaallllyyyyyyy hot while in neutral. I turn off the truck right away. Motor is still freakin hot. So, I go outside to open up the motor that smells bad and I discover that the amature is black. I scrape the black **** of the amature with a hex driver and it barely comes off. I then slip my finger thru the motor can and my finger is black.

My question is what the hell caused this? I want to try out another motor but I don't want this to happen to it also.