Most places cannot bench test the stater under a load - only free speed test. Which can be ok for a starter that is completely dead - but not very conclusive for a starter that works inefficiently.
I would do a starter current draw -
if too high -- mechanical binding or bad starter
if too low I rule out high external circuit resistance by doing voltage drop before replacing starter
If i am someplace I cannot test starter current draw I do the starter circuit voltage drop test first.
Watch the flowing you tube for some information regarding how to test starter circuit voltage drop
You should disable so engine will not start - pull fuel pump fuse or injector fuses. There will be 0 volts of voltage drop with 0 amps of current - this is why you test it with engine cranking -- current flowing!
https://youtu.be/U0OtjG4bwJg
Starter circuit voltage drop SUMMARY:
Positive side test
Connect Red lead of voltmeter to battery POSITIVE -- black lead to battery cable on starter
then crank engine while observing voltage - any thing higher than appox. 0.5 volts indicates high resistance (loose/ bad connections) on positive side of starter.
Negative side test
Connect red lead to starter case-- black lead to battery NEGATIVE
then crank engine while observing voltage - any thing higher than appox. 0.5 volts indicates high resistance (loose/ bad connections) on ground side of starter.
If either reading is too high -- remove ONE lead only and place at the next connection closer to the other lead -- repeat test
If the voltage reading is now good the part you skipped over contains the bad part/connection
If voltage reading is still too high then the bad part/connection is still between the meter leads -- move one lead again or replace the cable.
I hope this helps __ I do not use a remote starter - I just have someone else crank it for me or I use two long jumper wires with alligator clips on each end. I clip one end to test location and the other end to meter lead. The jumpers are long enough that I can place volt meter in car with me while I crank it.
Let me know exactly what your test results are I will try to help.
If you do not have a voltmeter??? then clean and tighten grounds. If you still have a problem either buy/borrow a voltmeter or start replacing parts until you get lucky.