I have a 4th gen iPad that I haven't used for so long that I forgot the PIN. I want to restore it to factory defaults as I plan to use it again. Everything I'm finding on this topic suggests that I need to use iTunes on a computer to accomplish this. Is this actually the case? Can't I use some combination of powering off/powering on and physical buttons to accomplish the same thing?
No amount of button pushing reloads the OS.
You can try to brute force the pin, you can try to log in if you already have jail broken the device, the only option to bypass the pin is to connect to USB and have iTunes or a similar sophisticated program speak with the firmware.
Once you've loaded things with iTunes (or substitute) then you have to deal with activation lock if you have that enabled.
Try to put the device in DFU mode and then you will be able to restore it.
Note: If the device is locked via iCloud account, you may be receiving errors while restoring and/or you may need to unlock the device first.
How to put the device into DFU mode:
- While the device is powered ON, hold down the POWER+HOME BUTTONS until the device shuts down, keep holding down the HOME button and plug the USB cable into the device.
- Open iTunes and it should find a device in Recovery mode.
There is only one way to force your iPad to reset if you do not know the passcode and do not have access to a computer. If you put in the wrong passcode 10 consecutive times, the iPad will automatically erase all data and then reset itself. This is only if this feature has already been set up in your general settings. It will take some time, because the more times you put in the wrong passcode, the longer the ipad will lock until you can try it again (1 minute, then 5, then 30, then an hour, then 24 hours for the tenth and final time). then, you do not need a computer or iTunes to set up you iPad...it will be like it is brand new.