Ulefone is a very good smartphone brand. But you might encounter other problems about network, sound, screen, etc after upgrade. Here's how to fix them.

1. Network issues

Q1. Why my Ulefone phone cannot find GPS signal when use 3G?
A1: It might be because 3G signal is weak.
A2: 3G is slower than 4G to detect GPS signal.

Q2. My Ulefone phone cannot connect to portable hotspot.
A1: Make sure you activated your SIM online services.
A2: Check your hotspot settings : set --> wireless & network --> portable hotspot.

Q3. The Ulefone cannot connect my car's Bluetooth speaker.
A1: Make sure the Bluetooth is enabled.
A2: Erase your Bluetooth connection history and try again.

Q4: I can't call or receive calls, why?
A: You have set something wrong on your phone, or your phone charge may be overdue.

2. Sound issues

Q1. I can't hear voice clearly during a call.
A: Move to a better place (no underground or places with too many people) to check if this problem is caused by weak signal, otherwise contact after-sales service.

Q2. No sound from headphone but the speaker works, what do I do?
A1: Make sure the volume of the audio player and of your phone are set properly.
A2: Use a cotton bud with pure alcohol to clean out the jack as it could be oxidized.
A3: Reset to factory default settings after backing up the files.
A4: Change headset and try again.
A5: Contact after-sales service for further assistance.

3. Screen issues

Q1. Part of the touchscreen doesn't respond, how to solve?
A1: Iif your Ulefone smartphone was not calibrated for a long time, calibrate the touchscreen first: set --> display --> screen calibration.
A2: Restore to factory default settings and try to calibrate again.
A3: Replace display or ask for after-sales service.

Q2. My Ulefone Phone's screen has weird colors!
A1: It is a software related fault, try to reboot or restore to factory default settings.
A2: Contact the after-sales service.

Q3. How to fix totally unresponsive touchscreen?
A: You need to replace the screen display or ask for after-sales service because there is something wrong in ribbon cable.

4. Bluetooth issues

Q1. Is the Bluetooth device in range?
A: The Bluetooth communication range for most devices, including your device, is about 30 feet. Be sure your phones are in range.

Q2. Remove the pairing and re-pair the Bluetooth device.
A: Removing the pairing, restarting your device, and then re-pairing the Bluetooth device refreshes and updates your connection.

Q3. Does your phone you're pairing with support the same Bluetooth protocols as your Device?
A: Refer to the Bluetooth device's user manual for compatibility.

5. Others

Q1. Why won't my phone recognize my SIM card?
A1: Make sure you have inserted the card correctly.
A2: Insert your SIM card in other phone. If it also can't be detected, change a card. If the SIM card can be detected in other phone, connect after-sales service.

Q2. HOME button gives no response, how to fix?
A1: Try to reboot your phone.
A2: Iit's a hardware malfunction, contact after-sales service.

Q3. My Ulefone cannot be detected by windows 10, why?
A: Change USB cable, because some USB cables don't support data transmission.

Q4. Unwanted pages often pop up and the calls hang up automatically.
A: It's a software or hardware related problem that happens in certain situations, e.g. charging. Contact the after-sales service if rebooting (or restoring to factory settings) doesn't work.

You may also want to read:
Ulefone Power 3 official flash tutorial
Ulefone Mobile Phone Official Flashing Tutorial
Ulefone Power 3 Official Android Oreo 8.0/8.1 Update FAQ
Solutions To Ulefone Smartphone Common Problems - WiFi, Bluetooth, Camera, SD, Sim, and More