Update problem on WR21

Digi TransPort WR21-L12B-DE1-SW
Huawei Technologies Co., Ltd.
ME909u-521 (12.636.12.01.00)

During firware update to we lost connection and onsite reboot wont get it back working.
error message: _deferred :: deferred polling(target firmware not running on router yet. it’s running

Is this a known issue. can it be fixed or do we need to factory reset them?

You are using VERY old firmware and unsupported cellular module
Also, 909ME was not certified in NA
Try recovering with a Flashwriter. Otherwise we have replacement routers. Please contact your local Digi distributor