none of the button combinations work.
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none of the button combinations work.
Were you trying to flash your firmware?
Welcome to Android Central! Are you following these exact steps? https://support.t-mobile.com/docs/DOC-34311
At very worst, you'll have to reinstall the firmware. See [Samsung] How to flash Stock ROM via ODIN. (If everything has been wiped from the phone [your data and apps you installed are more susceptible to that than Android itself is - so if Android is gone, all your stuff is gone too], and you haven't backed it, there's no way of recovering it, so don't bother asking.)
If it weren't a Samsung, and the bootloader was unlocked, you could try booting from boot.img (which you can get from a ROM zip) - I've gotten into a seemingly bricked Pixel that way more than once. (If it works, you just boot to the bootloader, then flash boot.img. That "no command" is the bootloader when it's been corrupted.)