Dell laptop won't show boot to usb option

[On2wheels]

It's a Dell Inspiron 15 3000 on the sticker but the bios shows 3505. I've checked the secure boot both on and off, and the list of bootable devices never gives a USB drive option.
What's odd is most youtubers show a more modern gui interface for selecting boot options but mine is the old school blue/grey screen, not sure why, I've force checked a bios update in the Dell software and it comes up blank.
Not too sure what I'm missing, I thought these things were pretty straightforward but nothing I do gets the USB option to show. Hopefully it's something simple and I'm having a seniors moment.

 

[moocow]

The answer I found on Dell forum points to a USB drive not created as UEFI boot-able. So if you made the OS install USB in Rufus, make sure CSM is turned off in option and try again?

Boot from usb option is missing from the bios | DELL Technologies

I made a live USB with parrotOS, even though the USB is being shown in the quick boot options, it is not been shown as a boot option in the bios. When I try booting from USB through the quick boot ...

www.dell.com

 

[On2wheels]

It's a Hiren's boot cd I made, don't remember how it was formatted, but I guess that could require remaking it.

 

[djbrad]

I got a laptop that does not show usb devices that aren't started quick enough, like a 2.5" hdd in a usb case.

I had to use usb flash drive or an ssd to get something.

Sometimes, I had to get into bios, then ctrl-alt-del once the hdd was spinning to get it in my boot menu.

My suggestion :

Disable secure boot. Get a usb flash drive, install ventoy on it in. Select GPT instead of MBR in the menu, format exfat, an drop an iso on it. Test if you can see it in the boot menu.

 

[Marzipan]

you have to hit F12 to load the boot menu just after post. if you have the USB key plugged in it will be one of the options showing.

I learned this recently as I bought the Dell G15 sswilson was selling and couldn't find the option in the BIOS either...so using my Google-fu I found out the above and that worked.