If we do that, we get the following in the kernel log of your laptop:
usb 1-1: new high-speed USB device number 6 using ehci-pci usb 1-1: unable to get BOS descriptor or descriptor too short usb 1-1: New USB device found, idVendor=0451, idProduct=d00f, bcdDevice= 0.00 usb 1-1: New USB device strings: Mfr=33, Product=37, SerialNumber=0 usb 1-1: Product: OMAP4430 usb 1-1: Manufacturer: Texas Instruments usb 1-1: USB disconnect, device number 6
We can also try to get a bit more infos with omap-usb-boot:
omap-usb-boot -w -v load u-boot.img Finding and opening USB device Found and opened omap4 USB device: OMAP4430 ASIC device id: 4430, HS device Loading and executing u-boot.img... Loading data with length 369176 bytes Bulk USB transfer failed Loading and executing failed
Here we know the device is signed because it's a "HS device".
If it was not signed it would print "GP device" instead.
There might be some pointers and interesting infos in the following link: https://www.lukastomek.info/2018/11/05/UnBrick-Samsung-Galaxy-Tab/