Does anything (ESC or motor) get really hot? You could have damaged a motor or ESC if you are lucky (better than 6 lipos). If it doesn't get hot, it is your batteries. By the way, if it is hot enough to burn you it is way too hot to run that way. ESC's should only get warm, and only from the BEC that powers your FC. I actually like to make sure my motors can be held firmly after a normal flight.
Check for cracks or other weak places. Rebalance props. Check for vibration without props.
Lipos are like living things. If you let them go dead even once they are not the same. Twice and you may as well throw them away. You can almost get away with it one time if you immediately recharge. No you can't wait till you get home.
Buy some of these and use them every time. They watch individual cell voltages which is much better than just watching total voltage. Adjustable alarm. Set it on 3.6v and land immediately when the alarm goes off; or 3.7v and you have 15 seconds more or so.
http://www.ebay.com/itm/1-8S-Lipo-Li-ion-Fe-Battery-Voltage-2IN1-TR-Tester-Low-Voltage-Buzzer-Alarm-CALA-/281835551727You can find more sellers by searching:
8s lipo alarm
on eBay.