Connect your network WAN to the ETH0
Connect your network LAN (laptop) to EHT2
Start shield, wait a few minutes.
Check if your laptop receives an IP address. (10.10.10.?)
Another way to check what is going on is using a console cable (where to get: link). This allows you to see what Shield is doing while booting - even if the web or SSL is not working.
A last option is to use TFTP to repair a broken stage 1 boot loader. I haven't done this myself, Roadrunner42 is one of the local experts ATM.
However since Shield is based on OpenWRT, it should be possible to replace a broken boot loader using TFTP. These are the links i've gathered just in case: