add case where no west workspace initialized to readme (#2975)

Author: aaravgarg

omi/firmware/BUILD_AND_OTA_FLASH.md

@@ -91,16 +91,33 @@ WEST_PYTHON="/opt/homebrew/Cellar/west/1.4.0/libexec/bin/python"
 $WEST_PYTHON -m pip install cryptography intelhex ecdsa click cbor2
 ```
 
-### 3. Prepare the Workspace
+### 3. Initialize the nRF Connect SDK Workspace
+
+If the `v2.9.0` directory doesn't exist or is empty, you need to initialize the nRF Connect SDK workspace:
 
 ```bash
 # Navigate to the firmware directory
-cd /path/to/omi/firmware/v2.9.0
+cd /path/to/omi/firmware
+
+# Create and navigate to the v2.9.0 directory
+mkdir -p v2.9.0
+cd v2.9.0
+
+# Initialize nRF Connect SDK v2.9.0 workspace
+west init -m https://github.com/nrfconnect/sdk-nrf --mr v2.9.0
 
-# Update West workspace (if needed)
+# Download all required repositories (this may take several minutes)
 west update
 ```
 
+**Note**: The `west update` command downloads approximately 1.5GB of source code including:
+- Zephyr RTOS
+- nRF Connect SDK modules
+- MCUboot bootloader
+- Various libraries and tools
+
+If the workspace already exists and is properly configured, you can skip to step 4.
+
 ## Building the Firmware
 
 ### 1. Prepare Configuration Files
@@ -226,6 +243,23 @@ cd ../omi
 cp omi.conf prj.conf
 ```
 
+#### Workspace Issues
+```bash
+# Error: No such file or directory: v2.9.0
+# Initialize the workspace first:
+cd /path/to/omi/firmware
+mkdir -p v2.9.0 && cd v2.9.0
+west init -m https://github.com/nrfconnect/sdk-nrf --mr v2.9.0
+west update
+
+# Error: already initialized in /path/to/omi/firmware
+# Remove broken workspace and reinitialize:
+rm -rf .west
+cd v2.9.0
+west init -m https://github.com/nrfconnect/sdk-nrf --mr v2.9.0
+west update
+```
+
 ### OTA Flashing Issues
 
 #### Device Not Found