All of the following are relevant questions:
1) What do you own and when? Is there anything you never own (e.g. which is licensed)?
2) Are license agreements a contract between the original purchaser and Meridian or something more ethereal, backed up in law? i.e. Are license agreements deemed transferable when the original purchaser sells on the product?
3) Has intellectual property been reverse-engineered or infringed?
4) Are you attempting to make money from reverse-engineering or infringement of IP?
5) Does Meridian mind?
Just considering these points:
1) As per my post above about the programs being sold as part of the product and not a separate entity.
2) Licence agreements do not apply to embedded programs unless specifically mentioned at point of sale or use.
3) If you change the PSU in your kit then you are defeating the designer's original design intention. For example, this might render the equipment unsafe and non-compliant to the EMC directive. If you change a bit of code in your microprocessor this may have similar or other effects as Gianni implies above. In neither case is IP the real issue.
4) If you do either of the above for commercial gain then you may be subject to action by the manufacturer or the authorities for infringing regulations or their registered design etc.
5) In the case of Meridian, they should only really be concerned about the scenario in point 4 if it has any meaningful commercial impact on them. If a patent or copyright infringement case goes to court then any damages awarded will reflect the likely loss suffered by the complainant. Litigating because you don't like something is poor business.