diff --git a/platform/drivers/keyboard/keyboard_ttwrplus.c b/platform/drivers/keyboard/keyboard_ttwrplus.c
index 462d1329..f1c4018c 100644
--- a/platform/drivers/keyboard/keyboard_ttwrplus.c
+++ b/platform/drivers/keyboard/keyboard_ttwrplus.c
@@ -113,7 +113,7 @@ keyboard_t kbd_getKeys()
      * The power key is only connected to the PMU and its state is detected through
      * the PMU interrupts.
      */
-    if (pmu_pwrOnBtnStatus())
+    if (pmu_pwrBtnStatus() == 1)
     {
         // Update the volume only once when key is pressed
         if (!(keys & KEY_VOLUP) && volume_level < 246)
diff --git a/platform/targets/ttwrplus/platform.c b/platform/targets/ttwrplus/platform.c
index 9dec316c..4679969e 100644
--- a/platform/targets/ttwrplus/platform.c
+++ b/platform/targets/ttwrplus/platform.c
@@ -107,6 +107,7 @@ void platform_init()
 
 void platform_terminate()
 {
+    pmu_terminate();
 }
 
 uint16_t platform_getVbat()
@@ -153,6 +154,11 @@ bool platform_getPttStatus()
 
 bool platform_pwrButtonStatus()
 {
+    // Long press of the power on button triggers a shutdown
+    uint8_t btnStatus = pmu_pwrBtnStatus();
+    if(btnStatus == 2)
+        return false;
+
     return true;
 }
 
diff --git a/platform/targets/ttwrplus/pmu.cpp b/platform/targets/ttwrplus/pmu.cpp
index ec3e7c62..31918937 100644
--- a/platform/targets/ttwrplus/pmu.cpp
+++ b/platform/targets/ttwrplus/pmu.cpp
@@ -40,7 +40,7 @@
 static const struct device *const i2c_dev = DEVICE_DT_GET(I2C_DEV_NODE);
 static const struct gpio_dt_spec pmu_irq  = GPIO_DT_SPEC_GET(PMU_IRQ_NODE, gpios);
 static XPowersPMU PMU;
-static bool pwrOnPressed = false;
+static uint8_t pwrOnPressed = 0;
 
 
 static int pmu_registerReadByte(uint8_t devAddr, uint8_t regAddr, uint8_t *data,
@@ -313,6 +313,13 @@ void pmu_init()
     printk("Setting Charge Target Voltage : %d\n", tableVoltage[val]);
 }
 
+void pmu_terminate()
+{
+    PMU.disableDC3();   // Turn off baseband power
+    PMU.disableALDO4(); // Turn off GPS power
+    PMU.shutdown();     // General shutdown
+}
+
 uint16_t pmu_getVbat()
 {
     return PMU.isBatteryConnect() ? PMU.getBattVoltage() : 0;
@@ -345,18 +352,15 @@ void pmu_handleIRQ()
 
     // Power on key rising edge
     if((irqStatus & XPOWERS_AXP2101_PKEY_POSITIVE_IRQ) != 0)
-        pwrOnPressed = false;
+        pwrOnPressed = 0;
 
     // Power on key falling edge
     if((irqStatus & XPOWERS_AXP2101_PKEY_NEGATIVE_IRQ) != 0)
-        pwrOnPressed = true;
+        pwrOnPressed = 1;
 
     // Power key long press
     if ((irqStatus & XPOWERS_AXP2101_PKEY_LONG_IRQ) != 0)
-    {
-        // TODO Shutdown radio, set platform_pwrButtonStatus to false
-        PMU.shutdown();
-    }
+        pwrOnPressed = 2;
 
     // Charger start IRQ
     if((irqStatus & XPOWERS_AXP2101_BAT_CHG_START_IRQ) != 0)
@@ -370,7 +374,7 @@ void pmu_handleIRQ()
         PMU.setChargingLedMode(XPOWERS_CHG_LED_BLINK_1HZ);
 }
 
-bool pmu_pwrOnBtnStatus()
+uint8_t pmu_pwrBtnStatus()
 {
     return pwrOnPressed;
 }
diff --git a/platform/targets/ttwrplus/pmu.h b/platform/targets/ttwrplus/pmu.h
index ef4bfe32..f6992b39 100644
--- a/platform/targets/ttwrplus/pmu.h
+++ b/platform/targets/ttwrplus/pmu.h
@@ -20,16 +20,59 @@
 #ifndef PMU_H
 #define PMU_H
 
+#include <stdint.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+/**
+ * Initalise the AXP2101 power management unit and power on the main power
+ * supply rails.
+ */
 void pmu_init();
+
+/**
+ * Shutdown the AXP2101 and remove power from all the power supply rails.
+ * Calling this function shuts down the device.
+ */
+void pmu_terminate();
+
+/**
+ * Get current battery voltage.
+ *
+ * @return battery voltage in mV.
+ */
 uint16_t pmu_getVbat();
+
+/**
+ * Control the baseband power supply rail.
+ *
+ * @param enable: set to true to enable the baseband power supply.
+ */
 void pmu_setBasebandPower(bool enable);
+
+/**
+ * Control the GPS power supply rail.
+ *
+ * @param enable: set to true to enable the GPS power supply.
+ */
 void pmu_setGPSPower(bool enable);
+
+/**
+ * Handle the AXP2101 IRQ flags.
+ * This function has to be called periodically.
+ */
 void pmu_handleIRQ();
-bool pmu_pwrOnBtnStatus();
+
+/**
+ * Get the current status of the power button input.
+ * The function returns zero if the button is released, one if is pressed and
+ * two in case of long press.
+ *
+ * @return current status of the power button.
+ */
+uint8_t pmu_pwrBtnStatus();
 
 #ifdef __cplusplus
 }