[SiriusHardware]

Hello Zed (Welcome to the forum) - I followed your link to 'srecord' but it appears that one of the few things it does not do is convert a straightforward ASCII text dump, although it can output to that format. The closest format it can load is 'ASCII-SPACE-HEX' which requires specific control characters at the beginning and end of the file, but is otherwise similar to a plain ASCII Hex dump.

Colin may have better luck in the short term if he can find a 'simpler' text editor (Maybe 'original' Notepad) to paste into, and inspects the pasted code for any oddball / extra characters or spaces and removes them before putting them through that online converter.

I might try modifying the present Arduino sketch so that it outputs Intel Hex, HxD may be able to cope with extraneous characters on the beginning or end of Intel Hex lines.