Thanks for the reply. The physical dimensions are 5cm x 5.5cm x 0.4cm (W x H x D)

My friend's Astell&Kern AK100 (aka iriver-rwa-ak100) stopped working, and I think the battery finally has died. The battery has the following markings: PR-665354N F121 00701AA 7.4WH 472246454746 3.7V 2000mAh. Li-ion battery. All links I have found (in this thread) seem to be dead, so if anyone...

Thank you, I will try to contact IRiver/A&K through those channels.

My friends Astell&Kern AK100 (aka iriver-rwa-ak100) stopped working, and I think the battery finally has died. The battery has the following markings: PR-665354N F121 00701AA 7.4WH 472246454746 3.7V 2000mAh. Li-ion battery. All links I have found (on this forum) seem to be dead, so if anyone...