U.S.-based network operator T-Mobile has resumed the sales of the ZTE ZMax phablet, but with a caveat attached - no removal of the battery please!

Earlier in April, T-Mobile was compelled to stop the sales of its variant of the popular ZTE Zmax, a T-Mobile exclusive, as some customers took it upon themselves to remove the device's non-removable 3400mAh battery. Fearing injury to customers, T-Mobile pulled the 5.7-inch ZTE ZMax phablet from shelves.

Why some customers chose to attempt the non-removal battery's removal is a mystery. They succeeded using screw drivers, knives and other tools as the back was merely clipped on.

Both ZTE and T-Mobile investigated the matter and have come to the conclusion that only a handful of users attempted the removal of the smartphone's battery. Now the smartphone is back on the shelves but T-Mobile employees have instructions they need to adhere to prior to the device's sale.

In a memo to its staff members, T-Mobile has instructed its employees to remind customers that the battery of the ZTE ZMax is not designed to be removed and the same should not be attempted. Only an "authorized technician" can do so per the carrier's memo.

"On Wednesday April 15, we temporarily suspended sales of the ZTE ZMAX to investigate a potential battery problem. That investigation (led by ZTE) found that the problem resulted from a very small number of customers attempting to remove the non-removable ZMAX back and battery. As a result, we are resuming sales of the ZMAX immediately. Going forward, inform customers considering the ZMAX that the back and battery are not removable (as stated on the original back cover cling), and attempts to do so can result in injury and will void device warranty," states the T-Mobile memo.

So from now on, T-Mobile staff will have to follow the protocol of informing customers purchasing the ZTE ZMax against battery removal as doing the same may void the smartphone's warranty, as well as cause injury.