TL;DR

1. Note: The entire process is lengthy and can be challenging to grasp initially. Take a look at the flow to get a general idea first.

2. Rational: I wrote this because I've encountered numerous obstacles myself and spent hours figuring out the solution. My goal is to share this knowledge and assist more people in overcoming similar hurdles.

3. My Twitter: https://twitter.com/eth_mikely.

Step 1/3: Get some Merlin_BTC for gas fee

Tips: When you met “Insufficient gas fee” error on Merlin website, it is because of lacking Merlin_BTC (Not M_BTC) as the gas fee.

1.1 Go to https://merlinchain.io/bridge, note the bridge gas gas per bridge transaction is 0.0003 BTC (L1 BTC)

1.2 Connect the wallet you staked your L1 tokens (Suggested). (Other wallet also works, but you need to send the bridged_BTC to the AA EVM wallet binding with your staked BTC wallet.)

1.3 Bridge some BTC from L1 to L2 Merlin chain.

• But how much? 0.0011 BTC per kind of token (Claim to L2 approval fee 0.00012 + Tx fee 0.000075 + Bridge back to L1 fee 0.0009), this may change based on the network congestions or L2 update.

1.4 Where is my Merlin_BTC (bridged BTC) after bridging?

• In your EVM wallet (Particle AA wallet) by clicking right-bottom floating button. (see screenshot below)

• Merlin_BTC contract address (in case you need to import the token in your EVM wallet): 0x24C1BD5c41D0b0813730B5895e9F343FB8477BEA(You can import it to the EVM wallet if you don’t see it)

Step 2/3: Claim your L2 staked M-xx tokens to L2 (Merlin Chain)

2.1 Once you got gas fee, you can follow the Merlin doc as below to complete this step. Guide:

2.2 How to verify if your token are claimed to L2?

Go to the AA EVM wallet by clicking the right-bottom floating button, import the token if you don’t see it by clicking + button as below.

Contract addresses: go to scan.merlinchain.io/tokens

and find the tokens prefixing with “Bridged_“, e.g. Bridged BRC20 rats (rats),

Step 3/3: Bridge back your tokens on Merlin L2 to L1 (BTC network)

3.1 Go to https://merlinchain.io/bridge

From = Merlin, To = Bitcoin

3.2 Wait and check if the tokens are in your L1 wallet, like Unisat or OKX wallet. (It may take 3-7 days usually.)

Thoughts:

1. Merlin chain is pioneering the BTC L2 ecosystem, they may have a good intention to compose EVM and BTC ecosystem and improve the user experience on wallet.

2. But:

   - The AA EVM wallet introduction make the flow very complex and difficult to understand, even for some middle level web3 onchain users.

   - The gas fee is more expensive comparing to ETH L2 or SOL, this may take more effort to improve for BTC L2s.

   - The speed is not good, much more than 1-3s.

The BTC L2 ecosystem has a long journey ahead, requiring not just engineers but also professionals in product managers and designers to create user experience. Additionally, comprehensive tutorials are also needed to assist individuals in navigating the steep learning curve.

Follow me at https://twitter.com/eth_mikely if it helps.