Is my motor shot

If you turn the key and it makes a tick that means the battery is dead. Maybe a shorted cell. Your motor isn't "dead" and the check engine light coming on means an emissions/driveability issue. Take the truck a local mechanic and I'm sure it isn't anything major. Since the CEL was on, you have a stored code a scan tool can read and that would point you in the right direction. Almost sounds like an EGR issue, or other sensor. But the coolant level was low you said. Did you happen to pull the dipstick and check the oil to see if maybe coolant isn't mixing in? If it looks like a chocolate milkshake it is, and you have a head gasket problem. Good Luck!

How much water did you have to add? If the coolant was low enough you could have been running hotter than what was showing on the temp gauge. This happens because the sensor is an immersion type, If its not in liquid it cant read the coolant temp. If you just get a click when you attempt to start could be several things. Starter, battery, solenoid or engine locked up. You should be able to turn engine over by hand using the pulleys.