The Nexus 6 just started rolling out to U.S. carriers, but the stock Android phablet may have already hit another speed bump. Motorola is apparently asking AT&T to return some early copies of the device over problem with its software.

Citing multiple anonymous sources and a leaked internal notice, Droid-Life reports that the bug makes the device pretty much unusable, turning the screen black and blocking it from finding a signal. The issue should only affect initial shipments, and Motorola is already working on a fix.

“We delivered a small number of Nexus 6 smartphones with incorrect software to AT&T customers who pre-ordered,” Motorola said in a statement to Phone Scoop. “The incorrect software prevents the phone from starting up properly. We will provide replacements for consumers whose phones are affected. The problem has been corrected and the phones currently shipping are fine.”