This procedure is greatly simplified: engine an APU bleeds off, fuel control off.
I have heard that the starter valve on this engine can be "exercised" to loosen it up if sticking, or that it can be manually controlled during a start attempt. But I haven't seen the procedure in writing. (Yet.)
Everything here is from the references shown below, with a few comments in an alternate color.
L Start Vlv Fail Open
R Start Vlv Fail Open
L-R Start Vlv Fail Open
Gulfstream GVII-G500 Airplane Flight Manual, Revision 4, August 29, 2019
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