Electra Jailbreak for iOS 11.2 - 11.3.1
Download the Electra jailbreak IPA file onto your computer.
Download Cydia Impactor from here.
Run the Cydia Impactor and drag the Electra IPA into it. Make sure to connect your device with the computer.
Provide your Apple ID Email and the Password to sideload the Electra app.
Go to device Settings --> General --> Profile & Device management to Trust the Electra app.
Disable Siri, Disable Passcode and keep your device AirPlane mode now.
Run the Electra app on your device. Restart your device for several times, before starting the jailbreak as a trick. Then click on the jailbreak button and wait for few seconds.