You have been sent a bad check. This check will appear good for up to a month, and after that will be clawed back from your account.
You will be asked to pay for your own gear. This will involve paying some apparent 3rd party through some means for your gear. This transfer will be arranged in a way that you cannot claw it back. Maybe via cash, maybe via other means. The scammers will know a way.
Your check will bounce, you'll be out the money for the gear you bought, and the gear will either not arrive or be junk when it does arrive.
As an alternative, you'll be asked for some banking information. Maybe for a deposit. They'll use this to make a fake check and try a similar scam on someone else. You'll be hit with bad checks and identity theft have to fight the bank about it.
Any phone number you have from any communication in the mail or email or the like was a fake one. If you talked to the bank on the phone and you didn't do it by completely independently finding that phone number for a bank you knew existed before this scam started, you didn't talk to a real bank.
If you did talk to a real bank, they told you that the check had cleared. But they are not bound by that, and the check is going to be designed to appear good for a long time before they find out it is bad. These guys are professionals, check clearing scams are old as mud.
The bank doesn't care, because they will get the money back from you.
To check if something is a scam
Only call phone numbers you find independently.
Don't trust anything they name, unless you know of it independently. Escrow, delivery company, bank - if they name it, assume it isn't trustworthy.
Physical presence. These type of scams rely on mass interaction and pseudo-anonymity. They are far less lucrative if they have to meet the people in person.
Refuse to act as a clearing house for other people's money. In an employment situation, money should flow towards you and only towards you. If they want to pay for something to send you, refuse to pay for it and get reimbursed for it. Money flows towards the worker, never away.
There are very, very, very few legitimate situations where you should spend money and get reimbursed for it in a new employment situation. And there are many, many, many scams based on it.