The Hardware is :
Car Headunit Erisin with Android 5.0.1 and Custom Rom Malaysk V13
with Google Play installed.
I bought Years ago the Version 2 of Poweramp that workt fine and
tried several times over the last two Years to intsall the Version 3 with
the Unlocker for V3 from the Google Playstore. The last Version i tried
was the V 893 but with all the Versions of V3 i treid i get this Bug :
Deinstalatin v2 and Unlocker v2 - ok
@resto you don't need to change any code - just enter the intent (often looking like cn.nihao.action.SHUTDOWN instead of android.intent.action.SHUTDOWN) into "Shutdown intent" Poweramp option. Usually can be googled by "shutdown intent YOUR HEADUNIT NAME".
Poweramp supports like 5-6 of these, but it looks like each headunit model/firmware (again for unknown reason) changes the intent name, so this is why Shutdown Intent option is there.