# Flashing problems


> The card reporting the wrong size, a card that will not format, and a Pi that will not boot after writing ScreenlyOS.
A few things come up often enough to be worth stating plainly.

## The Pi 4 or Pi 5 will not boot

A Raspberry Pi 4 stuck on a white screen, or a Pi 5 on a black screen with a blinking cursor, usually needs a bootloader update rather than a different image. See [Update the bootloader](/docs/screenlyos/hardware/raspberry-pi/guides/update-the-bootloader/).

## The card shows a much smaller capacity afterwards

A 16 GB card reporting 31 MB is expected. We format the card in a way Windows and macOS do not display correctly. The storage is all still there.

## The card is locked or read only

Full-size SD adapters have a physical write-protect switch on the side. Slide it away from the lock position and the card becomes writable again.