Bro, so you can open cydia right? Try not to reboot anytime till we'll fix it, don't let your phone die...
Go to cydia and search for "Cydia Eraser" or i think its just "Eraser" and install it (this will restore your phone freshly on ios 9.3.3 without updating it if you do it properly)
Before proceeding, take note of the following important points:
Make sure to take a complete backup of your photos and important things from your pc (don't use iTunes to backup). Eraser removes all the available data, apps and settings.
Do not interrupt Cydia Eraser while it’s working and make sure that your device has enough battery to let the process complete.
Cydia Eraser requires a working internet connection.
How to Use Cydia Eraser to Restore without updating:
Step 1: Launch Cydia.
Step 2: Navigate to the Search tab and search for Cydia Eraser.
Step 3: Open Cydia Eraser and install it.
Step 4: After the installation is complete, go to the Home screen. You’ll find a new icon labelled ‘Eraser’. Tap on it to launch the app.
Step 5: Read all the instructions on the screen and tap on “erase all data, unjailbreak device”.
Step 6: A prompt appears for confirmation. Tap on Erase All to proceed.
Step 7: Your device will reboot several times during the process. Make sure not to interrupt it while it’s working.
Step 8: Once completed, you will be taken to the welcome screen where you can setup your iOS device afresh and activate it. You can also restore from your backup during the setup process.
After following the above steps successfully, the Pangu jailbreak will be removed from your iOS 9.3.3 device and you’ll return to the stock firmware without being jailbroken. Your device will remain on the same iOS version as before, but with the jailbreak removed.
you can jailbreak your phone again!