iPhone 4 Won't Turn On After Application Crash

Hi Dave,
Ok, so tried holding the sleep wake button and the home button simultaneosly until the apple appears ( about 10 seconds) ? Disentfectant should not damage it unless it reached one of the two water sensors located within the device, highly unlikely.

See if you can force the phone into recovery mode:

Turn off your phone: Press and hold the Sleep/Wake button for a few seconds until the red slider appears, then slide the slider. Wait for the the iPhone to turn off. If you cannot turn off your phone using the slider, press and hold the Sleep/Wake and Home buttons at the same time. When your phone turns off, release the Sleep/Wake and Home buttons. Then, leave the USB cable connected to your computer, but NOT your phone, itunes running, press & hold the home button while connecting the USB cable to your dock connector, continue holding the home button until you see “Connect to iTunes” on the screen. You may now release the home button. iTunes should now display that it has detected your phone in recovery mode, if not quit and reopen iTunes. If you still don’t see the recovery message repeat these steps again. iTunes will give you the option to restore from a backup or set up as new.

I don't discharge/recharge often, usually just charging when it hits about 25-30%, would that have anything to do with it?

I doubt it, although Apple does recommend you fully discharge(let the battery completely discharge until the phone turns off) & then fully charge once a month-to maximize battery life. I suspect your problem was caused by the application crash. If your phone continues to function normally, don't worry about it. If the problem happens again, make an appointment at an Apple store.