Did you try the following tip?
For optimal performance after completing the guide, calibrate your newly installed battery: Drain it below 10%, then charge it uninterrupted to 100%.
I connect new battery terminal first. And two new adhesives put on the case instead of the battery. Finally, Put new battery to correct position on the case and push it.
If your iPhone is SIM free, you can activate with India SIM.
If your iPhone is not SIM free, you can use iPhone via Wi-Fi without activate when SIM is removed.
I agree. I have five times battery change experience. I didn't remove the front panel assembly and my repair done perfectly all.
If the speaker works fine when play music, I think your issue is caused the logic board or your carrier.
Try step 19 again and do carefully .
CAUTION: When reconnecting the digitizer cable, do not press the center of the connector. Press one end of the connector, then press the opposite end. Pressing in the center of the connector can bend the component and cause digitizer damage.