syncup not turning on

We just switched from Verizon back in May. I got my son the sync up watch and we upgraded it to a nicer screen protector, despite him using it sparingly it now will not turn on. I got a new charger and that worked for a second and now it’s won’t turn on again. I asked T-Mobile if this was a common problem for the longevity of this watch to be three months- and they said that I have no insurance somehow. 
 

Has anyone been able to fix this issue? I still owe on the watch and I need a device to be able to reach him. I am sorely disappointed with this as my gizmo had no issues.