Phone screen black, flickering or showing lines

Find out with a simple test: force restart the phone, wait a minute, then call it from another phone. If it rings or vibrates while the screen stays black, the phone is running and the display, or the cable that connects it, is the likely fault. Google suggests this exact check for Pixel phones and says that if the phone rings but the screen is still blank, it needs a repair centre.

If nothing happens at all, no ring, no vibration, no warmth on the charger, the problem is more likely power: see phone won't turn on.

• iPhone 8 and later (including Face ID models): press and release volume up, press and release volume down, then press and hold the side button until the Apple logo appears. Apple says this can take longer than 10 seconds.
• iPhone 7: hold the side button and volume down together. iPhone 6s and earlier: hold the Home button and the side or top button for around 10 seconds.
• Samsung Galaxy: hold the Power (Side) button and Volume down together for at least 7 seconds.
• Google Pixel: plug it in and hold volume up and power for at least 20 seconds. Google says a red light means the battery is fully discharged; charge it for at least 30 minutes.

A forced restart doesn't erase your data.

Google says that if a Pixel screen flickers, shows a green tint, or shows horizontal or vertical lines, you may have a hardware issue; its steps are to install any system update and, if that doesn't help, get it repaired. In our experience, lines and green tints usually follow a drop, pressure in a back pocket, or water reaching the display connector.

Samsung says flickering is usually a software issue, from app glitches or bugs, though a cracked screen can cause it. Turn off Adaptive brightness, raise the brightness if it only flickers when dim, then restart in Safe mode. Samsung says that if the flicker continues in Safe mode, it is likely a hardware issue.

Apple's first steps for an iPhone screen that doesn't respond, or responds only sometimes, are to restart, clean the screen, disconnect any Lightning or USB-C accessories, and remove cases and screen protectors. Google gives similar steps for Pixel: remove the case, screen protector and stickers, run the touch diagnostics in Settings, and try Safe mode. If the screen works in Safe mode, Google says a downloaded app is the likely cause.

Wet hands, sun cream and sand on the glass also confuse touchscreens at the beach. If touch still fails on a clean, bare screen after a restart, Apple says the device may need service.

At A1 Computers you can choose either, and you get the price of each before anything is fitted. Original screens cost more; compatible screens keep the cost down. The differences that matter, such as brightness, colour, True Tone on iPhone and what appears in Settings afterwards, are explained in original vs compatible phone screens.

Many screen repairs are done the same visit when the part is in stock. If the phone still turns on, back it up first; if the screen is completely dead, a new screen usually brings it back so you can.

It depends on the model and the screen you choose, so A1 Computers quotes for your phone. Send the model and a photo of the screen on WhatsApp to 641 780 077, call 922 71 35 82, or walk in to Local 4, Centro Comercial San Eugenio, Av. de los Pueblos 20, Costa Adeje, Monday–Saturday 10:45–21:30 or Sunday 10:45–14:00. You get the price before any work starts. Diagnosis costs €15.