add some changes & update images

_ont/ont-yotc-m2-2050-g40.md

@@ -28,13 +28,15 @@ parent: YOTC
 | Form Factor     | ONT                                                                    |
 
 
-# External Media
-
 {% include image.html file="yotc-m2-2050-g40-top.jpg" alt="YOTC M2-2050-G40 Top" caption="YOTC M2-2050-G40 Top" %} 
 {% include image.html file="yotc-m2-2050-g40-bottom.jpg" alt="YOTC M2-2050-G40 Bottom" caption="YOTC M2-2050-G40 Bottom" %}
 {% include image.html file="yotc-m2-2050-g40-pcb-top.jpg" alt="YOTC M2-2050-G40 PCB Top" caption="YOTC M2-2050-G40 PCB Top" %}
 {% include image.html file="yotc-m2-2050-g40-pcb.jpg" alt="YOTC M2-2050-G40 PCB Bottom" caption="YOTC M2-2050-G40 PCB Bottom" %}
 
+# Serial
+
+{% include image.html file="yotc-m2-2050-g40-ttl.jpg" alt="Serial Pinout (dont connect vcc)" caption="Serial Pinout (dont connect vcc)" %}
+
 ## List of partitions (MTD)
 
 | dev   | size     | erasesize | name          |
@@ -67,6 +69,24 @@ This ONT supports dual boot.
 
 Volumes `ubi_k0` and `ubi_r0` respectively contain kernel and rootfs of the first image, while `ubi_k1` and `ubi_r1` contain kernel and rootfs of the second one.
 
+# Useful files and binaries
+
+## Useful files
+
+User Configuration:
+```
+/var/config/config.xml
+```
+
+Custom Default Configuration:
+```
+/var/config/config_custom_default.xml
+```
+
+Hardware Configuration:
+```
+/var/config/config_hs.xml
+```
 
 # GPON/OMCI settings
 
@@ -162,11 +182,6 @@ mib set LAN_IP_ADDR 192.168.8.1
 reboot
 ```
 
-## Delete the ISP Default Configuration (it is recommended to back it up first)
-```
-rm /var/config/config_custom_default.xml
-```
-
 ## Enable Ethernet Ports
 ```
 mib set SW_PORT_TBL.0.Enable 1