iPhone 8 plus stuck on the apple logo and not accessing recovery mode

Perform a Forced Restart on the phone. Follow the instructions very carefully, as this is a bit tricky. You may need to repeat this several times.

Force restart iPhone - Apple Support

There are only 2 possible results when you perform a Forced Restart:

1) The phone returns to normal operation, non frozen status

or

2) There is a hardware problem with the phone that will need attention at the Apple Store (make an appointment) or at an authorized Apple Service shop

Find Locations

Response to : k_a_p ; iPhone Stuck on Apple logo

If you see the Apple logo or a red or blue screen during startup, try these steps:

Connect your iPhone to a computer. On a Mac with macOS Catalina, open the Finder. On a Mac with macOS Mojave or earlier, or on a PC, open iTunes. Find out which macOS your Mac is using.

Select your iPhone on your computer.

While your iPhone is connected, follow these steps:

On your iPhone 8 or later, including iPhone SE (2nd and 3rd generation): Press and quickly release the volume up button. Press and quickly release the volume down button. Then press and hold the side button.

Keep holding the buttons until you see the recovery mode screen.

When you get the option to restore or update, choose Update.

You will download the software for your device. If it takes more 15 minutes, your device will exit recovery mode. Repeat steps 2-4.