How to enter DFU mode with a broken power button

Hi,

I brought a broken iPhone 5g. Replaced the battery and screen and all went well.

But when I insert the sim, it says no service. I have checked all cables, everything is fine and I haven't damaged anything.

The date settings are also fine as it auto fetched it when I connected it to wi-fi.

I have been trying to do a hard reset, but power button doesn't respond becuase the phone is jailbroken.

I have an idea that clean installing a new iOS will help. However, my computer won't recognize the phone. There is nothing wrong with the charger as it charges well through wall-charger.