I recently purchased the SC-300 and forgot to screw on the pH storage bottle and probe was left to dry for a couple days. Is my pH probe ruined? If not, what should I do?

Place the electrode back in the storage solution as soon as possible. It may come back to life. Soak the probe in the storage solution (but make sure this solution is clean and clear) for a few days and then try and calibrate it and see what happens. If you do not have fresh storage solution you can soak it in the pH 4.01 reference solution until you are able to get fresh pH electrode storage solution.