Battery hookup proper sequence?

[Mikendebbie]

I have another thread going about my hydraulic system not working -but
What is proper sequence to re-install batteries?
I had them tested and they are fully charged.
I took pics as I took them out and I have hooked up cables under the battery box cover just like it was. The unit is unplugged from shore power.
I put the cover back on and hooked up both positive cables.
I touched the negative to the pole and it sparked.
Is that normal - should I just ignore?
Or am I doing something out of sequence?