Since most references to deep update would recommend Spark CLI it would be good to get this to work - once you got it you wouldn’t want to miss it anymore.
What are your troubles with it? What OS are you on? Have you seen this for example?
But since you said you can flash via USB, you’d just need the bin file and flash it. I’ll find it and post you a link here.
Edit: Found my local copy first - I’m sure there is a Spark one on GitHub, but just to get it to you ASAP 