This optional file can help you to synchronize your blockchain faster when you initially install Litecoin Cash. To use it, download the zip and extract bootstrap.dat into your LCC data directory. For Windows users, the default data directory is C:\Users\YOUR-USER-NAME\AppData\Roaming\LitecoinCash.
How I recovered from Trezor with LTC Segwit addresses (you should be able to apply these steps to get things working):
Transfer all coins off first Trezor to a different Trezor (you can then reset the original Trezor with new keys) OR transfer all Litecoin out of your prefork wallet into another wallet within Trezor/Ledger (wallet, not address). You will be putting your recovery seed into a computer during this so you may want to consider the recovery seed compromised when finished...
Do this on an offline computer using the downloaded version to be extra safe. You may want to consider this recovery seed burned — see above and transfer coins to new wallets not generated from recovery seed. With your original Trezor recovery seed, generate the private keys for addresses containing LCC here (using offline version & BIP49): https://iancoleman.io/bip39/ Copy those private keys to a text document. Make sure to get the "internal" / change addresses as necessary as well!
Download Litecoin Cash Core from litecoinca.sh and get the blockchain synced. See other guides for help with this. DO NOT IMPORT ANY PRIVATE KEYS YET.
Open the Debug Window, go to the Debug Console
Import the PK using "importprivkey YOURKEY LABELFORKEY false", repeat for each private key you want to import
Go to File -> Receiving Addresses (keeping debug console open)
In the Debug Console, run "addwitnessaddress ADDRESS” for each address listed in Receiving Addresses
Close the client, open up Terminal, navigate to install location of LitecoinCash-Qt and run “./LitecoinCash-Qt -rescan”, wait...
Once done, you should have your LCC