diff --git a/scripts/install/debug_install.sh b/scripts/install/debug_install.sh
new file mode 100755
index 00000000..3289cc14
--- /dev/null
+++ b/scripts/install/debug_install.sh
@@ -0,0 +1,81 @@
+#!/bin/bash
+# Quick diagnostic script to check why first_time_install.sh is failing
+# Run this on the Pi: bash debug_install.sh
+
+echo "=== Diagnostic Script for Installation Failure ==="
+echo ""
+
+echo "1. Checking if running as root:"
+if [ "$EUID" -eq 0 ]; then
+    echo "   ✓ Running as root (EUID=$EUID)"
+else
+    echo "   ✗ NOT running as root (EUID=$EUID, user=$(whoami))"
+fi
+echo ""
+
+echo "2. Checking if first_time_install.sh exists:"
+if [ -f "./first_time_install.sh" ]; then
+    echo "   ✓ Found ./first_time_install.sh"
+    echo "   Checking if executable:"
+    if [ -x "./first_time_install.sh" ]; then
+        echo "     ✓ Is executable"
+    else
+        echo "     ✗ NOT executable (fix with: chmod +x first_time_install.sh)"
+    fi
+else
+    echo "   ✗ NOT found in current directory"
+    echo "   Current directory: $(pwd)"
+fi
+echo ""
+
+echo "3. Testing argument passing with -y flag:"
+echo "   Running: bash ./first_time_install.sh -y --help 2>&1 | head -20"
+if [ -f "./first_time_install.sh" ]; then
+    bash ./first_time_install.sh -y --help 2>&1 | head -20 || echo "   ✗ Script failed or not found"
+else
+    echo "   ✗ first_time_install.sh not found"
+fi
+echo ""
+
+echo "4. Checking environment variable:"
+echo "   LEDMATRIX_ASSUME_YES=${LEDMATRIX_ASSUME_YES:-not set}"
+echo "   Testing with env: env LEDMATRIX_ASSUME_YES=1 bash -c 'echo ASSUME_YES would be set'"
+env LEDMATRIX_ASSUME_YES=1 bash -c 'echo "   ASSUME_YES would be: ${LEDMATRIX_ASSUME_YES:-not set}"'
+echo ""
+
+echo "5. Testing sudo with arguments:"
+echo "   Command: sudo -E env LEDMATRIX_ASSUME_YES=1 bash ./first_time_install.sh -y --help 2>&1 | head -20"
+if [ -f "./first_time_install.sh" ]; then
+    sudo -E env LEDMATRIX_ASSUME_YES=1 bash ./first_time_install.sh -y --help 2>&1 | head -20 || echo "   ✗ Sudo command failed"
+else
+    echo "   ✗ first_time_install.sh not found"
+fi
+echo ""
+
+echo "6. Checking /tmp permissions:"
+echo "   /tmp is writable: $([ -w /tmp ] && echo 'YES' || echo 'NO')"
+echo "   /tmp permissions: $(stat -c '%a' /tmp 2>/dev/null || echo 'unknown')"
+echo "   TMPDIR: ${TMPDIR:-not set}"
+echo ""
+
+echo "7. Checking stdin/TTY:"
+if [ -t 0 ]; then
+    echo "   ✓ stdin is a TTY (interactive)"
+else
+    echo "   ✗ stdin is NOT a TTY (non-interactive/pipe)"
+    echo "   This is expected when running via curl | bash"
+fi
+echo ""
+
+echo "8. Latest installation log:"
+LOG_FILE=$(ls -t /home/ledpi/LEDMatrix/logs/first_time_install_*.log 2>/dev/null | head -1)
+if [ -n "$LOG_FILE" ]; then
+    echo "   Found: $LOG_FILE"
+    echo "   Last 30 lines:"
+    tail -30 "$LOG_FILE" | sed 's/^/   /'
+else
+    echo "   No log files found in /home/ledpi/LEDMatrix/logs/"
+fi
+echo ""
+
+echo "=== Diagnostic Complete ==="
diff --git a/scripts/install/one-shot-install.sh b/scripts/install/one-shot-install.sh
index 6f5dd6ef..2213a7db 100755
--- a/scripts/install/one-shot-install.sh
+++ b/scripts/install/one-shot-install.sh
@@ -273,13 +273,15 @@ main() {
     if [ "$EUID" -eq 0 ]; then
         chmod 1777 /tmp 2>/dev/null || true
         export TMPDIR=/tmp
-        # Run in non-interactive mode with ASSUME_YES
+        # Run in non-interactive mode with ASSUME_YES (both -y flag and env var for safety)
+        export LEDMATRIX_ASSUME_YES=1
         bash ./first_time_install.sh -y
     else
         sudo chmod 1777 /tmp 2>/dev/null || true
         export TMPDIR=/tmp
-        # Pass environment variable for non-interactive mode and preserve TMPDIR
-        sudo -E env TMPDIR=/tmp LEDMATRIX_ASSUME_YES=1 bash ./first_time_install.sh
+        # Pass both -y flag AND environment variable for non-interactive mode
+        # This ensures it works even if the script re-executes itself with sudo
+        sudo -E env TMPDIR=/tmp LEDMATRIX_ASSUME_YES=1 bash ./first_time_install.sh -y
     fi
     INSTALL_EXIT_CODE=$?
     set -e  # Re-enable errexit