with key on you only have 8 volts at solenoid (brown) I would check for bad
battery/connections and have battery load tested to see if it is good

with a good battery and 12V going to solenoid brown with key on check for
12V to starter if no volt are at starter solenoid is bad. if with a good
battery and you do have 12 V at starter check for bad ground and connections
,

if battery and coinnections are good then starter is suspect do a voltage
drop test on the starting circuit see where the power is going is it is the
starter it will show up in this test.