For what it's worth now, you must use the MIPSR2 builds, not MISPR1.
It's actually written in the doc. tomatousb.org/doc:build-types
Now, you can try to enter the management mode by using the 30/30/30 method or the method indicated on this page:
If it does not work, maybe the wrt160n has a jtag that you can use to save it from death. If not, you're out of luck.