The bootrom update in fact is a rewriting procedure to a flash (EEPROM) memory located as an IC in the router. Router update can be made in to ways: with Xmodem protocol from boot menu or by command in vrp after uploading bootrom file. Usulaly the IC is 29F040B. Is a standard flash chip
Any mistake or failure during bootrom update will damage bootrom and router can not boot. Normal procedure is to send the equipment to HQ for repair. Another way is to rewrite the bootrom chip with a memory programmer attached to a PC. There are cses when we can not use any of this ways. There is another procedure, faster but Very Dangerous. The damaged bootrom can be rewrited using another bootrom IC by changing them in the router when router still running
This procedure is very dangerours. Any mistake can damage the hardware ireversible.
Here is steps to make this bootrom repareing (AR28-xx):
1- Open Case and identify flash IC - see:1.jpg
2- Get out the IC using a very thin screwdriver - see: 2.jpg
3- Put a plastic wire under the good IC and insert in the socket but not until the end just to make the connection between IC pins and socket pins - see: 3.jpg
4- Start the router and enter in the Boot Menu - see:4.jpg
5- Get out the IC using the plastic wire - see: 5.jpg
6- Put the damaged IC in the soket - see 6.jpg
7- Make bootrom update using Xmodem according to manual
9 - Reboot
Bootrom update can fail beouse of different causes:
- RS232 link is faulty during update
- Power off during update
- OS on PC create problems during update
- any other unpredictable problem
Any of this sittuation will couse bootrom to not work anymore.
This procedure is suitable in urgent cases when there is no time to send equipment back to HQ and there is no other equipment to replace. It is a DANGEROUS sollution but can save money and time.
Please pay attention to make no shortcirrcuit who can damage the router permanently