2017 S60 R-Design not starting
 

So yesterday my Volvo decided not to start. All of the dashboard and infotainment lights can turn on but it won't turn over. All I can hear is a clicking sound which I assume is the starter.

I had two people try to jumpstart my car thinking it was the battery but had no success. After an hour while I was waiting for a tow truck I tried again and it started.

Jump to today and it won't start again no matter how long I press the start button or even trying different keys.

Has anyone had trouble like this? i heard it could either be the starter, the battery, or the fuse/wires connecting the two. But my car only had 51,000 miles so in theory the starter should be fine.

I had the same issue on another car, 6-7 years ago. It was exactly like you described it - sometime it would start and sometimes it wouldn't, and jump-starting didn't work.... On that vehicle, the problem disappeared after an injector cleaning.

start simple. Check the battery voltage, then check your battery connections. Terminals should be tight, clean and the wiring/cables should not have any bubbles or swelling (a sign of corrosion which adds resistance, build heat, melts insulation...). You probably got it started yesterday because the battery finally built a charge and it drained out overnight. Your car is almost 5 years old which is about the typical life expectancy of a battery. PS - Injectors have nothing to do with your symptoms - a weak battery will turn on dash lights, click the starter solenoid but won't be able to spin the motor.

I'd probably buy a new battery then have the alternator/charging system tested. Even if the battery is not the root cause, at this point you'll need one soon enough. As to testing yourself, If you have a volt meter (a $20 Harbor Freight unit willl do fine), start by measuring battery voltage across the terminals with the car off. Anything over 12.6V should start the car. if you are lower, say 12.2V, your battery is drained. Anything way lower like 10V says you have a dead cell and need a new battery. So now if you are able to get the car jump started, next thing to do is to measure battery voltage with the car running. You should expect something in the 14 to 14.5 range. If you still see 12 or even a low 13, chances are your alternator (or voltage regulator) is wonky. Note some models have the voltage regulator as a replaceable part, others its part of the unit.

PS As a general best practice when jumping a car, hook up the cables and allow the helper car to run for 10 minutes before trying to start the car to make sure the battery has some juice it in to complete the circuit.