That’s exactly what I would expect on R29. Good, there is no continuity across the pins of C18.
So once you pulled C17, did the pedal start working?
Are you testing for continuity with the power on or off?…because it should be off.
If it is true that you are getting continuity across the pins of C17 after it is removed then that is a problem. You must have a solder short across those pins. Please fix it or re-test it for continuity. They should not be connected.
If you are getting continuity between any 2 pins of the ISP header then there are solder shorts across them or something else in that circuit. See the schematic for more details. You must be doing at least one thing wrong because one of the ISP pins should be connected to ground. Please re-test these pins.
The main question is did the pedal start working when you pulled C17? If not, check for continuity across those cap pins…fix it if they are shorted. If it did start working after you pulled the cap, then the fet is probably bad or the ISP header has a short across 2 of it’s pins.
-Brach