Improve User Experience in my software platform

Information for the business: We have a software platform that controls any type of machine or equipment
Industry: Technology
Design details: I have developed a software platform to control different kinds of machines and equipment around the world. The software platform user interface is very functional, it allows the user to view data and manipulate elements; however I have several challenges regarding the overall structure for the user interface:

(1) - The sales team complains that the UI is not intuitive, flat, and difficult to use
(2) - If a new user was to sign up and use the system, they wouldn't know what to do. If they knew our terminology they could figure it out, but if they don't then there isn't any guidance on how they can start using the system.
(3) - The target users of the system is very diverse. The system can be used to manage machines in many different industries:
* agriculture,
* manufacturing,
* retail etc..
The platform can also be used by many user profiles:
* CEOs (important for sales teams),
* Product Managers/R&D Managers (important for planning),
* Developers (important because they use our APIs to implement a solution).

To give you an idea of size: the platform we've developed so far, most of the intelligence is 'under the hood'. The total number of screens we've created so far is:
* home screen with map of machines
* device detail screen which allows user to control the machine, see previous commands
* user administration
* developer tools (4 pages) that allow user to create their own machine definitions
* rules administration (3 pages) to trigger commands when a machine reports a special condition.

If you're completely lost about the what we're doing, for background have a look at this competitor: http://www.ptc.com/internet-of-things/
Target audience: ceos, product managers, developers
Messages to communicate through the design: CEO said 'the ui has to be so compelling that we want our customers to login all the time'
Sales Manager: 'the ui needs to be intuitive so that the cost of on-boarding customers is easy for the user and cost-effective for us.
Ideas for the visual style: https://uxdesign.cc/
Where the design will be used: as part of software application design
Extra notes: I'm more interested in on-boarding process, user interface design, user experience, user workflow rather than graphics design.