The Well Audio
Thank you for the movie.
It looks like one or more relays are not switching.
Please, make and send a new movie with the following voltage measurements:
– J5 connector (exactly the voltage between the pins of the connector) with battery on (D4 LED on) and with battery off (D4 LED off)
– J4 connector (exactly the voltage between the pins of the connector) with battery on (D4 LED on) and with battery off (D4 LED off)
You should measure:
– J4 16V5 with battery on and 0V with battery off
– J5 16V5 with battery on and 13V with battery off
If the voltage on J4 is correct as above but you have 13V on J5 with battery off and 1V2 with battery on means that K4 is not working while K3_1 and K3_2 are working.
Otherwise, if you get 0V on J4 with battery on and off, 13V on J5 with battery off and 1V2 with battery on means that Q2 is broken (K4, K3_1 and K3_2 are not working).
You could use the part IRLML 0060 from Reichelt to replace Q2.