Unfortunately I've no schematic, but it is the same as this device that Dwaine posted with good photos
https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/msg985243/?topicseen#msg985243
U4 pins 7 and 8 go to PD1 & 2 on the micro
pin 1 & 4 is SW & Gnd
pin 5 & 6 go to P1 & P2
from the manual, see attachment.
2.7 Power off
The Multifunction Tester with automatic shutdown and manual shutdown.
? Automatic shutdown
When the component detection completed or IR decoding completed and after reaching the automatically shut down time, the tester automatically shut down.
Automatic shutdown time can be set by the hardware jumpers, timeout support for 10s, 15s, 20s and 25s. Factory set to 20s.
These are the other pinouts
#define TP_ZENER PA4 /* test pin with 10:1 voltage divider */
#define TP_REF PA3 /* test pin with 2.5V reference and relay */
#define TP_BAT PA5 /* test pin with 4:1 voltage divider */ This goes through a 1meg R only ?