✅ Add working GRUB repair solution

- simple_grub_repair.sh: Fixed GRUB boot issue successfully
- Direct GRUB installation without chroot complications
- Successfully creates debian EFI bootloader
- Resolves reset/reboot loop after LVM migration
- Tested and confirmed working

simple_grub_repair.sh

@@ -0,0 +1,85 @@
+#!/bin/bash
+
+# Simple GRUB Boot Repair Script
+# Direct GRUB repair without chroot complications
+
+set -e
+
+# Colors for output
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+BLUE='\033[0;34m'
+NC='\033[0m' # No Color
+
+VG_NAME="system-vg"
+EXTERNAL_DRIVE="/dev/sda"
+
+log() { echo -e "${BLUE}[$(date '+%H:%M:%S')]${NC} $1"; }
+error() { echo -e "${RED}[ERROR]${NC} $1" >&2; exit 1; }
+success() { echo -e "${GREEN}[SUCCESS]${NC} $1"; }
+warning() { echo -e "${YELLOW}[WARNING]${NC} $1"; }
+
+echo -e "${GREEN}=== Simple GRUB Boot Repair ===${NC}"
+echo
+
+# Check if running as root
+if [ "$EUID" -ne 0 ]; then
+    error "This script must be run as root. Use: sudo $0"
+fi
+
+log "Mounting external system..."
+mkdir -p /tmp/ext-boot /tmp/ext-efi
+
+# Mount the boot and EFI partitions
+mount "/dev/$VG_NAME/boot" /tmp/ext-boot || error "Failed to mount boot"
+mount "${EXTERNAL_DRIVE}1" /tmp/ext-efi || error "Failed to mount EFI"
+
+success "Mounted external boot partitions"
+
+log "Installing GRUB to external drive..."
+
+# Install GRUB directly to the external drive
+grub-install --target=x86_64-efi \
+             --efi-directory=/tmp/ext-efi \
+             --bootloader-id=debian \
+             --boot-directory=/tmp/ext-boot \
+             --recheck \
+             "$EXTERNAL_DRIVE" || error "GRUB installation failed"
+
+success "GRUB installed successfully"
+
+log "Checking installation..."
+
+# Check if GRUB EFI file was created
+if [ -f "/tmp/ext-efi/EFI/debian/grubx64.efi" ]; then
+    success "GRUB EFI bootloader created successfully"
+else
+    error "GRUB EFI bootloader not found after installation"
+fi
+
+# List EFI directory contents
+log "EFI boot entries after repair:"
+ls -la /tmp/ext-efi/EFI/ || warning "Could not list EFI entries"
+
+log "Cleaning up..."
+umount /tmp/ext-boot
+umount /tmp/ext-efi
+rmdir /tmp/ext-boot /tmp/ext-efi
+
+success "GRUB repair completed!"
+
+echo
+echo -e "${GREEN}=== Next Steps ===${NC}"
+echo "1. Reboot your system"  
+echo "2. Enter BIOS/UEFI settings"
+echo "3. Set boot order to prioritize external M.2 SSD"
+echo "4. Look for 'debian' entry in boot menu"
+echo "5. Boot from external drive"
+echo
+echo -e "${YELLOW}BIOS Settings:${NC}"
+echo "• Disable Secure Boot (if enabled)"
+echo "• Enable UEFI mode (disable Legacy/CSM)"  
+echo "• Set external M.2 as first boot device"
+echo
+success "External M.2 should now boot properly!"