go to the control panel in your computer, change view by to category in the top right corner if it isn't already that setting. Then go into hardware and sound, click on mouse and you should be able to see a disable click/touch pad. Click it, and now, it should be disabled.
Put the phone into DFU mode and restore it. If that doesnt work check the host file on the pc you are on, search reset the host file on windows (Version your on) and follow instructions and that should fix it. Sometimes this happens, when it cant receive the ssh blob from apples servers. So, it cant' verify the software and it wouldnt boot without the ssh blob because its one of the required files by the os to boot. Thats part of the reason that Jailbreaking is so hard sometimes because the devs of the jailbreak have to find a way around the boot security and a way inside the software itself.
If it only turned on for 3 seconds, it has nothing to do with the system itself. Probably has to do with the battery, try plugging it into a lightning cable and turning it on. If that doesn't work, plug into iTunes hold the home button while it starts up and try to put it into recovery mode. if iTunes recognizes it then hold the home and power for 5-10 secs till you see the screen turn off and then back on again. What ios version is it on? and is it Jail broken? Sometimes a tweak could be causing it to crash on boot and you may need to boot into safe mode. depending on what ios version your on it could have a different way of getting into it. Safe-mode is something that was installed if you installed cydia substrate. If you still cant get it to boot up regularly or into safe-mode, your best option is to restore it and restore from back up either via icloud or itunes
