e36 Won't crank-beeping constantly

[fls951]

Hi, My 1992 325is suddenly wouldn't crank the other day. Thought it might be the battery so I hooked up the jump pack and it started right up. Next start attempt (next day, new battery) no cranking again but I noticed that the car was beeping constantly. Key not in the ignition, doors closed. The beeping seems somehow related.

Have you ever encountered this condition?

Thanks in advance for your consideration.

Frank.