This does not work:
driver.find_element_by_xpath("//*[@id='theform']/div[2]/input").click()
driver.find_element_by_css_selector(".submit[value='Submit']").click()
The first invocation likely does not work because the input descendant node is most likely too vague and ambiguous.
The second invocation doesn't work because .submit[value='Submit'] is searching for (in english)
Any element that has class~="submit" AND value="Submit"
The value attribute matches, but not the class selector.
You could find that element with a quick CSS selector:
driver.find_element_by_css_selector("input[type='submit']")
See Effective CSS Selectors to see how to formulate good CSS selectors, and why this selector above would work.
//input[@type="submit"]or CSS selectorinput[type="submit"]. If it doesn't work, update your ticket with exception stacktrace