T-Mobile has suspended sales of the ZTE ZMAX phablet just 7 months after the device made its initial debut. According to sources close to ZTE, the carrier is unhappy with customers who are attempting to take out the handset’s non-removable battery.

TmoNews was first to report the sales suspension after it obtained a copy of a leaked T-Mobile memo.

“We’ve decided to suspend sales of the ZTE ZMAX at both T-Mobile and MetroPCS starting Apil 15, 2015,” it reads. “T-Mobile, MetroPCS and ZTE are currently evaluating the continued sale of this device.”

T-Mobile is asking staff not to sell any more ZMAX handsets until further notice, and to pull all inventory and any related materials from store shelves. Given that T-Mobile is the exclusive carrier of this handset, that means it’s no longer available in the U.S.

The carrier doesn’t provide a reason for the move in its memo, but a halt like this is almost certainly not due to poor sales; if that was the case, T-Mobile would likely just reduce the handset’s price to try to shift existing stock, then discontinue it.

According to sources close to ZTE who have been speaking to PCMag, the real reason for the suspension is “because customers were trying to remove the non-removable batteries on the phones.”

Why? That’s not totally clear, but one online tutorial suggests users are looking to pull the battery because the handset crashes and cannot be powered on.

Lots of smartphones ship with non-removable batteries these days, but the problem with the ZMAX is that it isn’t difficult to get inside it. While devices like the new Galaxy S6 and Sony’s Xperia Z series are glued together and hard to get into, the ZMAX’s rear panel is held in by a couple of clips that can be popped out with a small screwdriver.

But doing this could puncture the battery, and obviously that’s dangerous.

Perhaps ZTE will make it more difficult to get into the ZMAX and sales will resume later, but for now at least, the ZMAX is unavailable from T-Mobile.