I have a Mac book pro unibody 13 2010 that needs a firmware update and is supposed to support High Sierra. tryed various USB boot drives with no sucess

I then bought a bootable usb drive from Ebay ...

Mac operating systems may not be sold that way. It's a copyright violation that probably violates eBay's policies.

With the understanding that fact is only peripherally related to the problem at hand, I agree with HWTech that you should forget about using those "bootable" USB drives. By all means exhaust all those recommendations as you please but I believe the following will be the simpler solution.

That Mac shipped with OS X installation DVD-ROM discs. One for OS X itself and another for its bundled applications. If you no longer have them, then your next best option is to purchase a retail, white Mac OS X Snow Leopard DVD from a reputable aftermarket source.

It must be in a white box bearing an image of a snow leopard:

Apple no longer sells them. No authorized download sources exist, so if you find a site offering it to download it is a scam.

Boot from that disc, erase the Mac, and install Snow Leopard.

Then: at your option, update OS X using  > Software Update. That gives you the App Store. Then, update to the latest version your Mac can run through the App Store — in your case, High Sierra. Refer to How to download and install macOS - Apple Support. Once again, I reiterate the fact that no legitimate sources exist other than the one in that link. Obtaining it from any other source is a recipe for disaster.

We have no way of knowing what OS is provided on that USB stick you purchased on eBay. It may be some customized or specialized setup, or it may even contain malware. Even the USB stick may be faulty. Since we have no idea about this OS & USB stick we cannot use it to determine anything about your laptop. Ignore it.

Unfortunately the only way to create a bootable macOS USB stick is by using the instructions in this Apple article:

Create a bootable installer for macOS - Apple Support

This requires access to another Mac which is compatible with macOS 10.13 which is generally one from Late-2009 to 2018. Or you can create a bootable macOS 10.11 USB installer if you have access to another Mac generally from 2008 to 2015.

As for the Internet Recovery Mode option, make sure to use Command + Option + R to attempt to access the online macOS 10.13 online installer. However, some Macs may only boot to the online installer for the OS which originally shipped with the Mac from the factory (or latest available online which may be 10.7). Unfortunately the certificate for the older online installers are not expired so it requires setting the system date to some time in 2017 (may even need to set system date for High Sierra 10.13 installer to 2020 as I've seen a few reports of possible issues, but no one ever confirmed the issue).

What was the highest version of macOS ever installed on this laptop? Internet Recovery Mode is only available if macOS 10.12.6+ was previously installed at some point in the past.

Are you accessing local recovery mode or Internet Recovery Mode? At what point does the recovery mode installation fail? Does this laptop use a hard drive or an SSD? If it is the original hard drive, then it may be worn out or failing...an OS install very often reveals latent drive failures.

<< gives me a circle with a line thru it >>

That means that although the instance of MacOS appeared bootable, some major component was found to be defective or wrong version.

It has NOTHING to do with no firmware. Your Mac OS image is broken, and it won't boot because of that.

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also, There is no 'Live' CD like there is for linux. There is no such thing as a bootable MacOS drive (unless you make one by installing onto it), only bootable Installer drives.

in most models 2011 and later (except the Mac Pro 2012) Internet Recovery in in the Mac's ROM. in 2010 models, it's hit or miss, and in older models it's just not present, and you have to use other methods.

... just to add to what John Galt said, if you obtain a "Full Retail" DVD without the box, despite its gray-ish appearance, the full retail version has that same full color snow leopard picture on it. (Nose is pink, sky is blue-gray.)

Discs that are solid colors: orange, gray, or white, are for SPECIFIC models of Macs, and if not your exact Model, they WILL NOT boot or Install.