If you can find a name on the ESC you might find the manual online. Very often, RTRs will still use various brands of ESCs, receivers, etc. I think it pretty much has to have an LVC setting, though I'm not positive you can adjust. I'm certainly no expert, but it sounds more like battery related to me. When you shut down the first time and got another 5 sec, it sounds like the battery built up just enough charge to run another few seconds. Lowering or even eliminating the LVC setting would likely tell you whether it was the battery or not.