Hi @ramses2 ,
Don't know the particular remote but perhaps the contact surface on the underside of the remote start button is dirty or has worn away.
Usually with a lot of remote controls, when a button is pushed, the button’s contact surface “bridges” across the tracks on the circuit board below the button and this transmits the appropriate signal to the receiver.
You may have to open the remote up and check the button’s contact surface and the tracks on the circuit board. If they appear “dirty” use a Q-Tip, lightly moistened with Isopropyl Alcohol 99.9% (available for electronics parts stores) to gently clean the surfaces. If you have no IPA then use a clean soft pencil eraser and gently clean them.
Reassemble the remote and test.
If the button’s contact surface has been worn away and if the button contact surface appears to be of a silicone type material you can try using a pin to tattoo some electric paint -example only into the button contact surface to create a conductive surface.
Apply a very small dot of the paint to the button’s contact surface and then use the pin to tattoo it into the button. Allow it to fully dry (at least 24 hours), reassemble the remote and test. I have found that it you just apply the paint that it will come off as a spot of paint shortly after it has dried that is why it has to be impregnated into the button and allowed to completely dry.
Do not apply too much as this leaves little paint clumps on the board tracks after a few operations of the button and they will short out the remote so that it will not work at all. If this happens open the remote and wipe the tracks with a clean cloth. Eventually any excess paint will have been removed but it is annoying in the meantime having to do this a few times. After this it works as per normal.
Worth a try anyway.