Do you have a bench harness with at least two amps of 13.8 VDC support?
No... Do I need one? I've been reading/writing without benchtop harness since 1995.

I had it hooked to a battery charger while loading it,
It may be important to confirm the charger output is steady with no A/C component. If you have a spare battery or a jump pack that might be better.