Hi,
Try using 3u tools (free )
Start app, connect device, follow instructions for getting into DFU mode.
Keep holding button until app detects device.
App should display device detected in DFU mode (not Restore mode).
Select flash & download firmware if not already installed.
DFU mode is a much deeper restore process that normal restore can’t fix.
⚠️ Caution DFU is not recommended to use if device has been wet or damaged in some way as unrecoverable results may occur.
Hope this helps