Cannot connect JLink to DA14583 interface board

Hello,
I am trying to program my Dialog IoT sensor dongle using the interface board (as described in UM-B-065). I have connected a micro USB cable to the CIB port on the interface board. And I've plugged the IoT dongle into J5 on the interface board. Jumpers on the interface board are set up as:
* J14 in place
* J15 in place
* J16 in place
* SW2 is ON
* IoT dongle is OFF

I am able to establish a JLink connection using the JLinkGDBServer provided by segger (version 620e). But GDB exits without connecting to the CPU (see attached screenshot).
I have also tried connecting to the device using JLink Commander, the resulting output is:


\SEGGER\JLink_V620e>JLink.exe
SEGGER J-Link Commander V6.20e (Compiled Oct 6 2017 17:06:21)
DLL version V6.20e, compiled Oct 6 2017 17:05:40

Connecting to J-Link via USB...O.K.
Firmware: J-Link OB-SAM3U128 V3 compiled Sep 21 2017 14:14:50
Hardware version: V3.00
S/N: 483014369
License(s): RDI
VTref = 3.300V

Type "connect" to establish a target connection, '?' for help
J-Link>connect
Please specify device / core. : DA14583
Type '?' for selection dialog
Device>
Please specify target interface:
J) JTAG (Default)
S)门限
TIF>
Device position in JTAG chain (IRPre,DRPre) : -1,-1 => Auto-detect
JTAGConf>
Specify target interface speed [kHz]. : 4000 kHz
Speed>
Device "DA14583" selected.

Connecting to target via JTAG
不能测量红外len总。TDOis constant high.
不能测量红外len总。TDOis constant high.
不能测量红外len总。TDOis constant high.
不能测量红外len总。TDOis constant high.
Cannot connect to target.
J-Link>

I don't know how to proceed with flashing my code to the device.
Thanks for any help,