Fixes for the common problems.
Most Mars problems have simple causes, and the deep pool helps.
Almost always your Tor circuit or a temporary flood. Request a new circuit and retry, or switch to another address. With more live onions than most markets, one usually opens quickly.
If the header or login address does not match your bar, stop, close the tab, and copy a verified address fresh. A deposit that has not shown is usually waiting on confirmations.