[NOTE] - ALWAYS do a Hard reset or 30/30/30 on the router BEFORE and AFTER flashing a firmware build.
Hard Reset (aka 30/30/30 reset):
The following procedure will clear out the NVRAM and set dd-wrt back to default values:

* With the unit powered on, press and hold the reset button on the back of the unit for 30 seconds
* Without releasing the reset button, unplug the unit and hold the reset button for another 30 seconds
* Plug the unit back in, STILL holding the reset button for final 30 seconds (please note that this step can put Asus devices into recovery mode...see note below!)

This procedure should be done BEFORE and AFTER every firmware upgrade/downgrade.
Do not use configuration restore if you change firmware builds (different svn build numbers).
[NOTE] - For Asus units, the standard 30/30/30 method will reset the router but you will have to use the Restore button followed by a Power cycle. The only exception (so far) is the RT-N16 model. For this kind of model, follow the same method as introduced above but use the WPS button instead of the Restore button. If everything else fails it is also possible to reset by the command line (all units). Login to the router via telnet/ssh and select the command "erase nvram". This will reset the nvram partition to defaults for this type of router.

Find your router model name and write it in this field. The link to the DD-WRT database is here (http://www.dd-wrt.com/site/support/router-database). Then choose the router’s revision.

For WRT54G it is recommended to flash Mini-build at first. Download it to your computer.

Then download Vintage standard build. It is recommended.

Perform the 30/30/30. Go to routes firmware, update page and update it with mini-Build.

Then, the 30/30/30 once again. After reboot update it with Vintage Standard build.
Again 30/30/30 reset.