Vintage IBM AT 5170 Computer with IBM 5153 CGA Monitor and Model M 86 Keyboard

Description

Vintage IBM AT 5170 Computer with IBM 5153 CGA Monitor and Model M 86 Keyboard.
Please read the full description, as returns are not accepted.  Overall, this machine is in great shape.  Please do not hesitate to email me for questions or additional pictures.  Be very descriptive on any requests.
Included in this sale:
- (1) IBM AT (Advanced Technology) 5170 CPU - Configuration as shown
- (1) IBM Model M Keyboard ; Part # 1390131 ; Serial No. 1124379; Date 08 Oct 86. Plt No J1
- (1) IBM 5153 Color Monitor; Serial No. 1282165
- (1) Exploring the IBM Personal Computer AT 5 1/2" Floppy Disk 1521441
- (2) Power cords
Boot disk NOT included.
When I first powered it up, it would give me a 161 error. The 3rd picture shows the monitor working at this time.  This would normally indicate the internal battery is no good.  So I ordered a replacement battery pack for it.  But now when I power back up the monitor appears to recognize the start up of the machine and the machine makes the normal “beep” sound- but I cannot see the DOS prompt anymore.
If I hit F1 on the original keyboard, I can heard another beep, meaning the processor is working.  But the original monitor won’t display the dos prompt.  You can see it change color and react when plugged/unplugged  into CPU.
The only thing I did was replace the battery and I blew out the dust from the board with compressed air (while it I was shut down).  Any suggestions on what to test/fix would be welcomed.