Having trouble with BLE example

I am having trouble getting this example to run:

I merged the two python programs in order to get it more or less running.
I have the LED connected to D6 on the board.
I can see the device when I scan for devices with my phone.
I can also connect and pair with it using nRF.
The LED doesn't turn on.

# Helpers for generating BLE advertising payloads.

from micropython import const
import struct
import bluetooth

# Advertising payloads are repeated packets of the following form:
#   1 byte data length (N + 1)
#   1 byte type (see constants below)
#   N bytes type-specific data

_ADV_TYPE_FLAGS = const(0x01)
_ADV_TYPE_NAME = const(0x09)
_ADV_TYPE_UUID16_COMPLETE = const(0x3)
_ADV_TYPE_UUID32_COMPLETE = const(0x5)
_ADV_TYPE_UUID128_COMPLETE = const(0x7)
_ADV_TYPE_UUID16_MORE = const(0x2)
_ADV_TYPE_UUID32_MORE = const(0x4)
_ADV_TYPE_UUID128_MORE = const(0x6)
_ADV_TYPE_APPEARANCE = const(0x19)


# Generate a payload to be passed to gap_advertise(adv_data=...).
def advertising_payload(limited_disc=False, br_edr=False, name=None, services=None, appearance=0):
    payload = bytearray()

    def _append(adv_type, value):
        nonlocal payload
        payload += struct.pack("BB", len(value) + 1, adv_type) + value

    _append(
        _ADV_TYPE_FLAGS,
        struct.pack("B", (0x01 if limited_disc else 0x02) + (0x18 if br_edr else 0x04)),
    )

    if name:
        _append(_ADV_TYPE_NAME, name)

    if services:
        for uuid in services:
            b = bytes(uuid)
            if len(b) == 2:
                _append(_ADV_TYPE_UUID16_COMPLETE, b)
            elif len(b) == 4:
                _append(_ADV_TYPE_UUID32_COMPLETE, b)
            elif len(b) == 16:
                _append(_ADV_TYPE_UUID128_COMPLETE, b)

    # See org.bluetooth.characteristic.gap.appearance.xml
    if appearance:
        _append(_ADV_TYPE_APPEARANCE, struct.pack("<h", appearance))

    return payload


def decode_field(payload, adv_type):
    i = 0
    result = []
    while i + 1 < len(payload):
        if payload[i + 1] == adv_type:
            result.append(payload[i + 2 : i + payload[i] + 1])
        i += 1 + payload[i]
    return result


def decode_name(payload):
    n = decode_field(payload, _ADV_TYPE_NAME)
    return str(n[0], "utf-8") if n else ""


def decode_services(payload):
    services = []
    for u in decode_field(payload, _ADV_TYPE_UUID16_COMPLETE):
        services.append(bluetooth.UUID(struct.unpack("<h", u)[0]))
    for u in decode_field(payload, _ADV_TYPE_UUID32_COMPLETE):
        services.append(bluetooth.UUID(struct.unpack("<d", u)[0]))
    for u in decode_field(payload, _ADV_TYPE_UUID128_COMPLETE):
        services.append(bluetooth.UUID(u))
    return services


import random
import time
from machine import Pin
from micropython import const

LED_PIN = 6 #Pin D6 on RP2040 Connect ?

_IRQ_CENTRAL_CONNECT = const(1)
_IRQ_CENTRAL_DISCONNECT = const(2)
_IRQ_GATTS_WRITE = const(3)

_FLAG_READ = const(0x0002)
_FLAG_WRITE = const(0x0008)
_FLAG_NOTIFY = const(0x0010)
_FLAG_INDICATE = const(0x0020)

_SERVICE_UUID = bluetooth.UUID(0x1523)
_LED_CHAR_UUID = (bluetooth.UUID(0x1525), _FLAG_WRITE)
_LED_SERVICE = (_SERVICE_UUID, (_LED_CHAR_UUID,),)


class BLETemperature:
    def __init__(self, ble, name="NANO RP2040"):
        self._ble = ble
        self._ble.active(True)
        self._ble.irq(self._irq)
        ((self._handle,),) = self._ble.gatts_register_services((_LED_SERVICE,))
        self._connections = set()
        self._payload = advertising_payload(name=name, services=[_SERVICE_UUID])
        self._advertise()

    def _irq(self, event, data):
        # Track connections so we can send notifications.
        if event == _IRQ_CENTRAL_CONNECT:
            conn_handle, _, _ = data
            self._connections.add(conn_handle)
        elif event == _IRQ_CENTRAL_DISCONNECT:
            conn_handle, _, _ = data
            self._connections.remove(conn_handle)
            # Start advertising again to allow a new connection.
            self._advertise()
        elif event == _IRQ_GATTS_WRITE:
            print("Accessing LED")
            Pin(LED_PIN, Pin.OUT).value(int(self._ble.gatts_read(data[-1])[0]))
            
    def _advertise(self, interval_us=500000):
        self._ble.gap_advertise(interval_us, adv_data=self._payload)
        
if __name__ == "__main__":
    ble = bluetooth.BLE()
    temp = BLETemperature(ble)
    print ("Running")
    
    while True:
        time.sleep_ms(1000)

I added print statements for debugging the interrupts and I am getting all of the interrupts serviced but one:

    def _irq(self, event, data):
        print ("Interupt Handler")
        # Track connections so we can send notifications.
        if event == _IRQ_CENTRAL_CONNECT:
            print("Connect Interupt")
            conn_handle, _, _ = data
            self._connections.add(conn_handle)
            
        elif event == _IRQ_CENTRAL_DISCONNECT:
            print("Disconnect Interupt")
            conn_handle, _, _ = data
            self._connections.remove(conn_handle)
            # Start advertising again to allow a new connection.
            self._advertise()
            
        elif event == _IRQ_GATTS_WRITE:
            print("Accessing LED")
            Pin(LED_PIN, Pin.OUT).value(int(self._ble.gatts_read(data[-1])[0]))

I am not sure what the _IRQ_GATTS_WRITE routine does. Can anyone help ?

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