[MTCD  Android Head Units Q&A] drcooksamsungace:
Erisin Recovery instructions

Erisin Reset Instructions. Erisin 7886 PX5 Head Unit (LM Model MCU)

Note: All actions at Own Risk ! All Care No Responsibility.

For Erisin 7886 unit (but instructions may be useful for others)

Note: Power Button is on top LH Side of panel.

Reset Button is a micro switch within a recessed hole on the top RH side of the panel and looks just like similar recessed holes in the other corners of the panel which is a confusing PITA.

A plasticised paperclip (slightly thicker than a normal paperclip & easier to grip) with one end twisted out at a right angle to form a handle with the other end forming a reset pin works best – accessing the reset micro switch is fiddly and seems rather fragile so I found the paperclip better than a mobile phone reset key etc. for easily triggering the switch without mashing it or fumbling about).

Note: For any PX5 Reset on any device it seems you have to press a combination of power / reset keys 3 TIMES in the correct sequence to trigger the Recovery mode – the combination of keys seems to differ between models (some posts indicate 3 presses of reset keys, some 3 presses of power button, do a Chicken Dance, etc. the Erisin 7886 PX5 uses both Power and Reset keys – Go Figure) - but the 3 Times Press requirement seems to remain the same.

For the Erisin 7886 (and probably some other models)

•	Hold the Power Button until Head Unit buttons & Panel Lights start Flashing – (I found this can be done with black (bricked) screen or on start/restart or while head unit is on and running normally with no ill-effects).

•	Release Power Button as soon as lights STOP flashing (about 2-3 seconds), then Immediately after (within 1 second), Press the Reset Button using Paperclip and hold down for 1 Second, Let Go of Reset Button, - wait 1 second then Press Reset Button Once Again for 1 Second, then release Reset button.

•	Wait. System may go blank for about 2 minutes or so, or even longer for a bricked unit trying to recover. Go away and have a coffee. Do not press any other buttons. It should then go into Recovery

Mode.

•	If you have an SD or USB card in the slot the unit may go into a weird multicoloured recovery screen looking like something out of The Matrix. Do not panic, remove the SD card and it should then go into recovery mode. It appears to be trying to reboot off the card but removing the card will allow it to resume its’ normal operation.

•	Experience is that if does not restart, then button press timing/sequence is wrong, (i.e. released Power Button before flashing sequence completed, took too long between button presses or held too long, pressed extra buttons afterwards – anything like this can upset the sequence) - or the machine needs an opportunity to reset by having the power removed altogether for a while. Turn ignition off - pull keys out to completely remove power from the unit (often remains on ACC if keys are left in) and wait for ½ hour.

Appears Head Unit retains memory for some time and re-powering just resumes where it left off in its’ stuck state if it has not rebooted/recovered or left off for some time.

Hope this helps - Good Luck.