Hi,
the WiFi firmware can be updated from the GUI but the EVSE firmware needs a programmer to do it.
The one I use is this https://smile.amazon.co.uk/dp/B07DLZPV7Q?psc=1&ref=ppx_pop_dt_b_asin_title
There is a whole thread on it it is quite long but there is a lot of good info in it Upgrading OpenEVSE / EmonEVSE Controller Firmware using ISP programmer - Integrations / OpenEVSE - OpenEnergyMonitor Community
John