Xiaomi R3G connecting PC to UART

I succesfully installed LEDE on my new Xiaomi R3G, but after upgrading it with "lede-ramips-mt7621-mir3g-squashfs-sysupgrade.tar" it stopped working.
Restarting device does not helping.
I'm thinking about connecting PC to UART using my RS232 (DB9) on PC in this way::
UART-RX -> PIN 2 on DB9
UART-TX -> PIN 3 on DB9
Is it correct, or should I use UART USB converter?

tried the failsafe mode?

You mean to start router in failsafe mode? I dont know how to do that.


Thank You jwoods.
OK. Now I understand what safe mode is,but the problem is that I cannot connect to my device.
It has UART port on motherboard. I thought about connecting through this UART port.
And my qustion is, if I connect rs232 port in my PC directly to UART port on my Xiaomi Router 3G.