TMS570LS3137-EP: Trouble Halting Target CPU: (Error -2062 @ 0x0) Unable to halt device.

I am using CCS10.1.1 and XDS100 USB JTAG to connect to TMS570LS3137 development board. 
Looks like the pre-loaded code is preventing JTAG connection and I am getting the following error

Trouble Halting Target CPU: (Error -2062 @ 0x0) Unable to halt device. Reset the device, and retry the operation. 
If error persists, confirm configuration, power-cycle the board, and/or try more reliable JTAG settings (e.g. lower TCLK).

I looked into the below link 
software-dl.ti.com/.../ccsv7_debugging_jtag_connectivity_issues.html
"If you are unable to connect to a flash-based device, keep in mind that pre-loaded code may prevent it from properly connecting. 
Changing the boot mode of the device or performing a mass erase can recover from this situation, however, there are instances where the device is locked permanently and 
will require replacement."

I tried using UniFLASH tool to erase the entire FLASH. Still getting the same error. 

Is there a way to erase the FLASH contents using CCS or anyway for JTAG to reestablish the connection with MCU?

Note: JTAG scan test passes.

Please help.

Jai